dwindling FPS due to "quirk" of the sim?

[HappyHaddock]

Hi,

 

Some of you may be aware of the mods I'm working on to try and enhance the lighting and skies in this sim. Part of this work has involved a lot of testing and optimisation to try and avoid slowing things down, where by-and-large my work in progress mods run at roughly the same speed as the stock game.

 

My tests have, however, highlighted a strange phenomena which I spent a long time trying to attribute to my mods, but ultimately felt must be an inherent quirk of the game and tests in mods off mode have showed the same "problem" to exist and to have nothing to do with my own mods.

 

When I first load a mission it runs fine at a satisfactory frame rate. Most people "playing" this sim would then run the mission until complete or they were shot down. However in testing and fine tuning my mods I've reason to be repeatedly loading the same mission and then reloading again to run it for only a few seconds just to check the look of things under different times of day.

 

I've noticed the first time you load then the FPS is as would be expected but there seems to be some sort of retained memory or cache clearing problem meaning that when loading and shutting down  the same mission a few times that by about the third load exactly the same scenario with identical settings is running at approx. half the FPS it did when  I first loaded it just a few minutes earlier.

 

I don't see this being a major, or even minor, problem for most users under ordinary circumstances but it is making life difficult when trying to monitor the performance hit of making minor changes to fine tune my mods.

 

I just wondered if anybody else had encountered a similar drop in FPS when running the same mission more than once , or if they have any suggestions as to what may help clear this. Completely shutting down IL2 when I finish a mission and then going back to the game launcher to start again avoids the dwindling FPS, but it does result in spending longer opening and closing the software than actually testing settings in my mod.

 

If this isn't just a technical issue with my own PC then for those of you who do suffer a slow running sim it may be something to think about in terms of "boosting performance" by periodically shutting down Il2 completely and re-starting the software rather than just re-launching straight back into the same mission if shot down?

 

Cheers

 

HH

 

 

 

Edited April 22, 2019 by HappyHaddock

[Dutch2]

. The only thing I ever noticed that I could never reach more than 60fps (max) while in normal cases it was max 90fps in VR. Even settings from auto to 90 in Win10 did not bring any change. After a while this decrease in FPS was gone, I still suspect an Steam secret update being responsible for that, other wise nothing was changed. 

One thing I also noticed that the sun in my VR glasses, does have impact on the frame-times, so maybe the lighting by the sun also needs lots to calculate, for shining,  reflection and shadows. Could you try it only now shadows and mirrors complete off and see if the FPS now drop much lesser. 

1 hour ago, HappyHaddock said:

 

When I first load a mission it runs fine at a satisfactory frame rate. Most people "playing" this sim would then run the mission until complete or they were shot down. However in testing and fine tuning my mods I've reason to be repeatedly loading the same mission and then reloading again to run it for only a few seconds just to check the look of things under different times of day.

,

 

Edited April 22, 2019 by Dutch2

[HappyHaddock]

17 minutes ago, Dutch2 said:

. The only thing I ever noticed that I could never reach more than 60fps (max) while in normal cases it was max 90fps in VR. Even settings from auto to 90 in Win10 did not bring any change. After a while this decrease in FPS was gone, I still suspect an Steam secret update being responsible for that, other wise nothing was changed. 

One thing I also noticed that the sun in my VR glasses, does have impact on the frame-times, so maybe the lighting by the sun also needs lots to calculate, for shining,  reflection and shadows. Could you try it only now shadows and mirrors complete off and see if the FPS now drop much lesser. 

 

 

Thanks

 

I'll give it a try out of curiosity to see if the sun/reflections makes a difference but unless there is some strange reason the sim retains some memory of these being used in previous missions but not other graphics settings it seems unlikely to be the cause.

 

Principally these have been direct like for like comparisons the only thing I was changing when first noticing this problem was the time of day (which may affect the reflections by changing the position of the sun), but even that I stopped changing when testing to try identify the cause of this FPS problem. So if it is any kind of in game setting that did slow things down I'd have thought those same settings should have also slowed down the frame rate the first time I loaded each mission as this problem occurs with multiple re-loads even when I don't change any settings.

 

Cheers

 

HH

[Dutch2]

To not being confused inhere, you are talking about the FPS difference between two of the same missions, the only difference is the time of the day. 

 

About the memory I know Nvidia does remember its shader cache, only I would expect  the Fps would be even higher. I’m not at my computer but this cache can be disabled in the Nvidia CP or being cleaned by the Windows disc cleaning tool. 

 

 

 

[HappyHaddock]

1 hour ago, Dutch2 said:

To not being confused inhere, you are talking about the FPS difference between two of the same missions, the only difference is the time of the day. 

 

About the memory I know Nvidia does remember its shader cache, only I would expect  the Fps would be even higher. I’m not at my computer but this cache can be disabled in the Nvidia CP or being cleaned by the Windows disc cleaning tool. 

 

 

To be clear, I first noticed the problem when testing the look of my mods at different times of day, but once I was aware of the problem I would test the same mission in mods-off mode  with out any changes, I'd simply shut it down and immediately reload exactly the same mission, by about the third time I was reloading it was running much slower than the first time despite having absolutely identical settings.

 

HH

 

 

[Semor76]

No. He´s talking about loading the same mission again with the exact same parameters as before. I get those FPS drops as well. Only solution is to shut down the sim & restart it again.

 

Edit: HH was faster.. ?

Edited April 22, 2019 by Semor76

[Dutch2]

If you both can publish that specific mission, members could give it a try. As speaking for myself, I sure would like to test it. 

Edit: I do not need the mod only the mission, sounds not that difficult I guess. 

 

BTW, do you both have an HD or an SSD? 

Edited April 22, 2019 by Dutch2
asking for the mission

[JonRedcorn]

Sounds like a possible memory issue. 

[HappyHaddock]

It's not a particular mission, it seems to be any mission;

 

just bung in any settings into the quick mission generator, fire it up, check the FPS then shut it down and fire it up again to check the FPS on the second launch, by the third or fourth time I start it I am  experiencing a significant drop in FPS compared to the first time despite running exactly the same settings.

 

I don't have an ssd just regular HD.

 

Cheers

 

HH

[JonRedcorn]

1 hour ago, HappyHaddock said:

It's not a particular mission, it seems to be any mission;

 

just bung in any settings into the quick mission generator, fire it up, check the FPS then shut it down and fire it up again to check the FPS on the second launch, by the third or fourth time I start it I am  experiencing a significant drop in FPS compared to the first time despite running exactly the same settings.

 

I don't have an ssd just regular HD.

 

Cheers

 

HH

That's why I said it sounds like a memory issue.

[Dutch2]

4 missions in VR using the Sturmovik 1942 in a single quick mission 12:00h autum, flying at autopilot and just like you starting from the airfield. 

I did do 4 missions and I have logged it into FCAT-VR, but I see no difference between them, same at my ingame fpsVR Steamsoftware, it did show nothing difference.  BTW, the spikes in the logs are the sun, yes it is a very sunny mission.  Keep in your mid I'm not flying in the flat wold but using VR, maybe that could explain the difference?? 

 

edit: Forgot something normally I use an overclock when playing BoX, but because you both have an mid/low range system, I use the stock speed, RAM, CPU & GPU. 

 

  

Edited April 22, 2019 by Dutch2

[JonRedcorn]

1 hour ago, HappyHaddock said:

It's not a particular mission, it seems to be any mission;

 

just bung in any settings into the quick mission generator, fire it up, check the FPS then shut it down and fire it up again to check the FPS on the second launch, by the third or fourth time I start it I am  experiencing a significant drop in FPS compared to the first time despite running exactly the same settings.

 

I don't have an ssd just regular HD.

 

Cheers

 

HH

Just tested it myself, saw absolutely no drop in framerate. Loaded a kuban mission 5 times, the same one, no drops. Probably something to do with your mods. Game works just fine.

Edited April 22, 2019 by JonRedcorn

[Dutch2]

6 hours ago, Semor76 said:

No. He´s talking about loading the same mission again with the exact same parameters as before. I get those FPS drops as well. Only solution is to shut down the sim & restart it again.

 

Edit: HH was faster.. ?

What do you have an HD or SSD?

 

[Semor76]

38 minutes ago, Dutch2 said:

What do you have an HD or SSD?

 

Still on HD but will make the step to an SSD this summer.

[JonRedcorn]

Who knows could be the 3.5 gb of memory on the 970, or the older computers you guys are running, like I said I loaded the the same mission multiple times, saw 160 fps each time.

[JUSTPLANECRAZY]

Hi guys i have been having the same trouble but only in quick missions which i do tend to fly the same one multiple times, i have not noticed anything in campaign though it seems to be fine, i can actually run campaigns on higher frames than quick missions and it runs silky smooth even when things are pretty hectic compared to the very little whats going on in quick missions and i am on ssd wd blue.

[HappyHaddock]

Well from the replies here it's sounding more like an issue particular to my PC, or at least older PC's if others with newer computers can fire up the same mission time after time without experiencing any loss off FPS.

 

My PC is now around five years old, possibly a touch more (i5 3570k  16Gb ddr3 RAM gtx970). I tend to favour running all graphics settings maxed out and when I run aps that monitor performance during IL2 the four cores of the CPU tend to run at 30-40% usage rarely spiking above 50%, memory tends to stay below 25% usage with the GPU naturally running flat out to achieve best FPS (even if that best isn't as high as some would deem tolerable).  There is no discernable difference in the usage data between a high FPS mission and running the same mission when it delivers low FPS which makes it difficult to pin point any particular part of my PC that might be the cause. However as others have said it is possibly a memory thing so I'll have to start exploring that as a possible cause. I can however say it's not related to mods as running the stock game in mods -off mode still shows the same problem.  

 

HH

[JUSTPLANECRAZY]

I agree i do use mods but i have ran it without the mods and still get the same trouble it looks bloody awful if im honest after being able to run fortress stalingrad with my ultra settings i have not changed anything anywhere, my system is only a few months old and i have had my brother who built it run all tests on hardware and he says everything is fine he knows what he is doing it was his his bread and butter not so long ago, i dont have a clue what the issue is and although it is a pain in the arse at least i now know that im not alone on this one. 

In the above thread from JonRedcorn regarding a memory issue that was the first thing my brother thought it was as well, but like i said tested everything and zilch.

[JonRedcorn]

I wonder if its an HDD vs SSD issue possibly. I suggest deleting the startup.cfg file and seeing if that does anything. I know it's pretty much my fix all at this point but it really does work a lot of the times.

Edited April 23, 2019 by JonRedcorn

[Velxra]

The problem stems from the graphics card and the game engine. There has been a long standing issue since roughly 2014 where performance is hit on the GTX 960, 970, 1050, and 1070 cards. The issues were reduced/improved late last year. However many of the problems still remain. Tweak the game for the best performance via settings and that is good as it will be.  It's an issue from the game engine itself and not our desktops.  The cause of the problems have been buried in new layers of game code since 2014 so the devs have a difficult time solving this issue. 

Your memory leak issue is directly related to the old constant micro stuttering problems. I hope this can at least narrow your search path a little. It is a lessor known issue in the community.

@SAS_Storebror is probably the most knowledgeable on the topic.

A couple related threads. They may or may not be related as much of the old game coding talked about has been changed.

*read page 2*

 

 

 

Edited April 23, 2019 by Geronimo553

[ShamrockOneFive]

18 minutes ago, Geronimo553 said:

The problem stems from the graphics card and the game engine. There has been a long standing issue since roughly 2014 where performance is hit on the GTX 960, 970, 1050, and 1070 cards. The issues were reduced/improved late last year. However many of the problems still remain. Tweak the game for the best performance via settings and that is good as it will be.  It's an issue from the game engine itself and not our desktops.  The cause of the problems have been buried in new layers of game code since 2014 so the devs have a difficult time solving this issue. 

Your memory leak issue is directly related to the old constant micro stuttering problems. I hope this can at least narrow your search path a little. It is a lessor known issue in the community.

@SAS_Storebror is probably the most knowledgeable on the topic.

A couple related threads. They may or may not be related as much of the old game coding talked about has been changed.

*read page 2*

 

 

 

I eventually figured out that the cause of my stutter in the thread that I started way back then was caused by two things:

 

1) A weird bug with IL-2 that Jason identified in a thread. Turning on 4K textures seems to fix it.

2) The limited 2GB of VRAM that my GTX 960 had. If I was able to keep it at 1.6-1.8GB then I was fine. Hit 1.9GB and it was very stuttery. I solved that with a new GPU that has 8GB of VRAM. ?

[SAS_Storebror]

3 hours ago, ShamrockOneFive said:

I eventually figured out that the cause of my stutter in the thread that I started way back then was caused by two things:

 

1) A weird bug with IL-2 that Jason identified in a thread. Turning on 4K textures seems to fix it.

2) The limited 2GB of VRAM that my GTX 960 had. If I was able to keep it at 1.6-1.8GB then I was fine. Hit 1.9GB and it was very stuttery. I solved that with a new GPU that has 8GB of VRAM. ?

 

Thanks @ShamrockOneFive, this absolutely makes sense.

In my case, after a major hardware upgrade (new Mainboard, CPU and RAM) I'm suffering from micro-stutters even more than before, at least it feels like.

While in low-medium populated areas everything's fine and I get more or less stable 100+FPS, high-massive populated areas, especially when being populated with lots of different AI actors, causes massive microstuttering, especially when moving your head around quickly or turning the plane.

It's much more noticeable inside the cockpit than on external views to me.

 

Now that we need to enable 4K textures to be potentially stutter-free, the GPU VRAM usage of course increases with it.

And if many different actors are visible in the same spot, and the textures of all of them don't fit in the VRAM at the same time anymore, the system needs to load/unload textures while you're looking around all the time.

My GTX 970 has 4GB VRAM, but only 3.5 GB have the full bandwidth. Seems like as soon as I get closer to that limit, the stuttering starts.

Add to that, since Microsoft rolled out the Spectre/Meltdown patches, with microcode-updates for newer CPUs, I get the feeling that especially latest CPU series (Intel 8000 and 9000 for instance) suffer badly from certain limitations applied for security reasons, which is probably why on my newer rig, even though the frame rates are much higher than on the old one (i5-9600K vs. i5-2500K), the stuttering even feels worse.

 

Mike

[HappyHaddock]

Thanks folks for chiming in with various thoughts and ideas, sometimes reports of technical probs don't get the same response from the community here as posts with pretty pictures and exciting videos...

 

Anyway it is both reassuring and alarming in equal measure to hear that this is an issue affecting others, reassuring to know it's not that there's something inherently wrong with my PC if the same problem can affect new PC's, but alarming that there's no clear consensus about what needs to be done to solve the problem.

 

HH

 

[HappyHaddock]

Well I've tried a few more tests and it is looking like the most probable culprit is Graphics card memory but that is far from conclusive. 

 

There was a mention in some of the threads linked above that Vsync might help and it sorts of makes a difference...

 

I initially thought having Vsync turned on was solving the problem as after five re-launches of the same mission, aside form the first second or so of each re-launch having a wildly fluctuating FPS it settled down to where I'd expect it based upon how the mission runs the first time I load it. However by the sixth re-launch it failed to settle at where it should be and remained at approx. half the expected FPS, subsequent re-launches of the same mission continued to show the problem.   

 

I tried the same expt. on a much earlier and less technically demanding map.  I don't know if having Vsync on actually solved the problem there or simply "bought" me enough extra re-launches of the mission that I got fed up waiting for the next re-launch to show the drop in FPS...

 

On a simple mission just sitting on an empty runway on the Lapino map the sim started up multiple times, each one at around 70+FPS with Vsync turned on, whereas without V-sync by about the third or fourth launch I was seeing that drop to about 40FPS.  The same test of starting up a mission just sitting on an empty runway on the Kuban map would first launch at 45+ FPS. With Vsync on I got about five or six relaunches before FPS dropped to about 20. With Vsync turned off I only got about 3 re-launches before I saw the same FPS drop.

 

HH

[JUSTPLANECRAZY]

Hi guys thanks for the info i have always run it with 4K turned on and v sync off because my system didnt seem to be running right with it on , and as for GPU im using a 1080ti the only thing i have done lately is update nvidia drivers twice and all the old crap that it doesnt remove has been done manually, BLOODY GREMLINS there somewhere but im not going to quit this damn machine aint going to get the better of me forever, if or rather WHEN i find the culprit i will post. THANKS again guys much appreciated.? 

[Dutch2]

Think the problem was a massive FPS reducement on  @HappyHaddock rig, after flying a couple of exactly the same missions, not stuttering problem or is here an relation between the two?

I and @JonRedcorn did testings, we did not find any problem, as the game is the same, so it must be or wrong adjustments or the hardware.

While this FPS problem is only after a couple of the exact the same missions, it must be both the guys hardware, both guys running low spec systems. Running on a HD,  Vram, memory leak as all being wrote down, but this could also be thermal throttling of an hardware component, that because running low range rig is reacting in this case very extreme. 

Computer life is also tweaking and testing. ?

 

Edit: regarding if having Vsync problems, one trick when I did use when playing in the 60hz flatworld, disable Vsync, in BoX and in Nvidia CP. Play the game in Windowed mode and now you will use the Windows desktop Vsync, normal this is rather troublefree. Also to avoid the not needed high spikes and waste of GPU power, by capping the max. frame-rates to the refresh-rate of your monitor. 

Edited April 23, 2019 by Dutch2

[Velxra]

I personally found the most gains by turning vsync off and changing the maximum pre-rendered frames to 1 in the nvidia control panel for the il-2 exe.  Currently testing fast vsync right now so cannot comment if it is better or not than vsync off.

*edit*
With fast vsync enabled I notice very slight micro stutters when looking at shadows/reflections in the cockpit. When I turned off vsync these tiny micro stutters went away. I also tried running with 4k textures on and off with the changed vsync settings and I noticed no change with 4k textures on or off. 

Edited April 24, 2019 by Geronimo553

[HappyHaddock]

Well I could have done without a day chasing diagnostic work but...

 

After wasting a lot of time addressing a corrupted windows update that failed to apply (second one in almost as many months) and getting that sorted the problem still  remained and so I spent time focussing on various memory checks.

 

Not a single ap or memory check utility reported any fault, every one reported 8GB of RAM working faultlessly... however my machine has 16GB installed, except windows and Bios can only find 8GB to test.

 

For a PC the age of mine 8GB is probably all that most would expect it to have and it seems fine for running most regular activities, but it seems likely there has been some sort of hardware failure on one of my 8GB sticks of Corsair DDR3.

 

Quite why (or even if?) this is the cause of the strange way that the FPS would drop with subsequent re-loads of the same mission in IL2 I don't know, but  for the relatively modest costs involved I'm going to order and replace all the RAM in my PC and use it as a chance to upgrade to the fastest DDR3 the motherboard will take.

 

Then I'll start again with new tests to see how my PC behaves and if replacing the RAM has cured the issue?

 

In the mean time is anybody aware of a utility that can actually detect faulty/failed RAM to conclusively prove it is a hardware fault with the RAM, and not some setting somewhere that has "disabled" part of it. I've switched the chips around in the various slots on the motherboard and which ever of the four slots I plug the two 8GB sticks into it sill only detects a maximum of 8GB so I'm fairly confident it s a hardware failure, but it would be peeving to replace the RAM and find my PC will still only detect 8GB despite having a maximum capacity on the motherboard for 4x8GB, and when until recently it ran fine with 16GB.

 

HH

 

[Dutch2]

So it appears to be an hardware failure, I do hope its is not what I had, an dying  Asrock P67 motherboard, that also started as an not all RAM is detecting in the Bios and startup failures.  

 

https://www.howtogeek.com/260813/how-to-test-your-computers-ram-for-problems/

 

Edit: and btw you can also download this little tool https://www.cpuid.com/softwares/cpu-z.html  that shows your RAM and its speed. 

Edited April 24, 2019 by Dutch2

[HappyHaddock]

43 minutes ago, Dutch2 said:

So it appears to be an hardware failure, I do hope its is not what I had, an dying  Asrock P67 motherboard, that also started as an not all RAM is detecting in the Bios and startup failures.  

 

https://www.howtogeek.com/260813/how-to-test-your-computers-ram-for-problems/

 

Edit: and btw you can also download this little tool https://www.cpuid.com/softwares/cpu-z.html  that shows your RAM and its speed. 

 

Thanks for the reply,  Windows own memory check utility mentioned in your first link is something I had already ran three times when trying to get it to recognise the second stick of RAM but it would not recognise it, it just kept saying there were no faults with the 8Gb it could detect. As for other utilities I've tried various that supposedly track RAM usage and speed, but so far none have found the other 8GB to actually monitor it.

 

So until the new memory arrives I'm running half the memory I used to have, and running in single channel format may further slow things down compared to when it was running as paired dual channel. It's been quite noticeable that  various other bits of "more demanding" software have been slow to open over the last couple of days, and most particularly they have been slow to populate lists when clicking on any kind of "file open" tab or "save as" tab, and  even something "simple"  like selecting a font/typeface in Word is taking a little longer to populate a list of choices from the moment you click the mouse.

 

Any kind of slow down on retrieving data does hint at memory problems so I'm hoping that one stick of failed RAM is the only source of my problems and it's not indicative of bigger issues?

 

HH

 

[Semor76]

On 4/23/2019 at 7:19 PM, Dutch2 said:

Edit: regarding if having Vsync problems, one trick when I did use when playing in the 60hz flatworld, disable Vsync, in BoX and in Nvidia CP. Play the game in Windowed mode and now you will use the Windows desktop Vsync, normal this is rather troublefree. Also to avoid the not needed high spikes and waste of GPU power, by capping the max. frame-rates to the refresh-rate of your monitor. 

Dont want to derail this topic too much, but I have a question:

 

Due to my rather weak GPU, I use this trick for all my games.No matter if Flight sim, RTS stuff or other games.

Now, one of the last updates here with IL-2 brokes this trick for me. It happend only with IL-2, all other games running fine. So I have to check Full Screen & Vsync again.

 

Maybe do you have a workaround for me?

Edited April 24, 2019 by Semor76

[Dutch2]

12 minutes ago, Semor76 said:

Dont want to derail this topic too much, but I have a question:

 

Due to my rather weak GPU, I use this trick for all my games.No matter if Flight sim, RTS stuff or other games.

Now, one of the last updates here with IL-2 brokes this trick for me. It happend only with IL-2, all other games running fine. So I have to check Full Screen & Vsync again.

 

Maybe do you have a workaround for me?

 

Since Black Friday 2018 I’m not playing in the flatworld anymore, but I know for sure, before that date, the trick of running in the desktop Vsync did work. Now it could be that you  disabled this  in Win10. I know in Win7 it was the aero that needs to be enabled, I thought in win10 this was not the case anymore. 

Maybe do a Google search on that. 

[Semor76]

2 hours ago, Dutch2 said:

 

Since Black Friday 2018 I’m not playing in the flatworld anymore, but I know for sure, before that date, the trick of running in the desktop Vsync did work. Now it could be that you  disabled this  in Win10. I know in Win7 it was the aero that needs to be enabled, I thought in win10 this was not the case anymore. 

Maybe do a Google search on that. 

Thx. I will do that. Maybe one of those Micro$ofts glourious updates has broke this little trick.

 

Edit: 2 min. with Google and I´ve found it. The Win 10 gamemode enables the forced Vsync,even in Windowed mode. Reinstalling the Win10 gamebar solve the problem.

Edited April 24, 2019 by Semor76

[HappyHaddock]

"Curiouser and curioser said Alice"

 

Well...  Having tried my old RAM in every configuration of the four slots in the mother board it would only recognise 8GB of the total of 16GB whatever I did so I assumed I'd had a hardware failure on one of the paired sticks of RAM.

 

Consequently I've ordered another 16GB (2x 8GB) and now they have arrived in the post I've taken out the old and put in the new.  It took a little while to boot up the first time as presumably various registry files and other such memory related stuff were updated by Windows, but by the time it had opened my desk top it was running smoothly and quickly again and actually showed as having 16GB of RAM... All good and well.

 

I know there is various debate about the benefit that running memory in paired dual channel has compared to a single stick of the combined total capacity of two matched sticks, and that where the mother board supports it (which almost all do) it is generally felt better to go with paired.  However the general consensus is that if you have a spare stick of  RAM lying about it does no harm to plug it into a vacant slot even if it can't be accessed as quickly as had it been paired as dual channel with double the band width... So rather than waste the one remaining good stick of old RAM I thought I'd install it and take my total up to 24GB.  

 

Well damn me if I can work out which of the old sticks has failed.  The two old sticks installed  together without the new RAM are detected as 8GB, either one installed on its own is still showing as 8GB and all four sticks (both new and old installed together ) show up and run as a total of 32GB.

 

God knows what is going on but I now have a PC with a gratuitously excessive 32GB of RAM way out of proportion for the needs of a 7yr old PC.

 

Anybody have any suggestions as to which strings the gremlins are pulling the background?

 

HH

 

[ZachariasX]

17 minutes ago, HappyHaddock said:

Well damn me if I can work out which of the old sticks has failed. 

If you ate insure about such, memtest86+ is a useful tool to give you a better idea. Just make runs with only one DRAM in and you‘ll see if it returns errors. To be really hopeful for having a working product, you should do at least overnight runs.Even though some might return errors right away. Windows10 however also has a built in memory test that you can select in safe boot. Still, I‘d prefer memtest86.

 

I would never halve read/write speed by not having a pairwise configuration. And if you see the task monitor use more than 16 GB, then buy another pair for 32 GB. But few applications use that.