Overclocking CPU solves graphical instability

[carlR]

I was having a lot of problems with unstable graphics - terrain underlay showing through/flashing shadows & objects/redrawing etc & it was ruining the game for me. This was despite having an 8800gtx 768MB!Tried different drivers/lowering settings etc but nothing worked. Eventually I decided to overclock my 2.4Ghrtz dual core CPU to 3.15Ghrtz. What a difference it has made! Now got smooth graphics & scrolling and enjoying the game immensely.

So to those of you with graphics issues despite having powerful GPU's it is the speed of your processor that is likely to be causing the problem.

And to BFC......are you going to recode this game for dual core compatibility, since as it stands at present dual core users are unlikely to have enough power to run the game properly.

[YankeeDog]

Huh. I wonder what's causing this. . . I also have a 2.4GHz dual core CPU, but only a so-so ATI 256MB 2600PRO (In an iMac, but it shouldn't really make any difference when I'm running it as a PC in Bootcamp).

But I've never had any significant graphics issues; I can run the game with all graphical settings maxed out in most scenarios. On the really large, complicated maps, I do have to back off on the settings a bit to keep the framerate up, but not very much; the game still looks great.

So it's not solely a CPU issue; it must be some combo of CPU + GPU that puts a heavier load on the CPU.

But at any rate, AIUI, BFC has already tried to re-compile the code for dual core once, but it didn't work due to a problematic Micro$haft compiler. I think it's on the list to try again, but I have no idea when.

Cheers,

YD

[carlR]

YD

Interesting. So it seems to be a mismatch between CPU & GPU. I basically needed either a less demanding GPU or a more powerfull CPU. It kind of makes sense.

[YankeeDog]

Ya, it sounds like the superfast GPU is somehow overloading the CPU.

I don't know much about how these things work, but it seems to me there should be some way of adding a routine to the code that "dumbs down" the GPU (when necessary) so that it doesn't overload the CPU.

Or maybe it's not really worth the effort to add this to the code, if BFC expects to get dual-core functionality working soon. Now that most of the major bugs in the game engine are worked out, hopefully they'll have more time to spend on stuff like this.

Cheers,

YD

[Redwolf]

I highly doubt that this theory is true. Putting a slower graphics card into the original un-overclocked PC won't make it better.

CM is just a very CPU-intensive game.

You overclocked to the speed that the fastest and most expensive CPUs in the world have now. Of course it improves performance

[YankeeDog]

So why do I get better performance, then, with the same CPU (pre-overclock) but a much weaker GPU?

Better motherboard?

More memory? (I do have 4gb installed)

Apple engineering magic? (I kid, I kid)

Or something else, like less other stuff taxing the CPU? Since I mostly use the "Windows side" of my Mac for very little other than gaming, it runs a very bare bones WinXP and nothing else. Could that be the difference?

[Redwolf]

Originally posted by YankeeDog:

So why do I get better performance, then, with the same CPU (pre-overclock) but a much weaker GPU?

It seems obvious that CMx2, NVidias drivers, and the newest fastest cards don't achieve the full potential of those cards.

It would be possible that the NVidia drivers had to do some (CPU) work on newer cards that they don't have to do on older cards.

[Redwolf]

If anybody want to debug this:

You need dual monitor. On the non-game monitor you open task manager, the CPU utilization, sorted by CPU. (there's also network login stuff to see this without second monitor)

If the above theory is correct, then a high CPU usage would be observed in some kernel modules, as opposed to the CMx2 application.

Then you compare that picture between a machine with a 8800 card and a machine with a lesser card. You might have to compute out the different CPU speeds to see who's doing how much work there.

[Pzman]

Also keep in mind that Intel CPUs will throttle back under heavy load if it is getting too hot, so make sure your system has a good aftermarket cooler rather than the stock Intel one.

But at any rate, AIUI, BFC has already tried to re-compile the code for dual core once, but it didn't work due to a problematic Micro$haft compiler. I think it's on the list to try again, but I have no idea when.

Umm, then why does task manager show CM as using both Cores (1.08)? On my system CMSF never uses more than 50% of both cores (2.2Ghz C2D), since the task is split.

[Redwolf]

Originally posted by Pzman:

</font><blockquote>quote:</font><hr />

But at any rate, AIUI, BFC has already tried to re-compile the code for dual core once, but it didn't work due to a problematic Micro$haft compiler. I think it's on the list to try again, but I have no idea when.

Umm, then why does task manager show CM as using both Cores (1.08)? On my system CMSF never uses more than 50% of both cores (2.2Ghz C2D), since the task is split. </font>

[YankeeDog]

*Shrug* I dunno. . . IIRC, Steve made some sort of comment back about December that they had tried to re-compile the code to take better advantage of dual core processors, but that it hadn't worked. But maybe I'm getting things mixed up; I'm not particularly inclined to go off and dig for it as the game is working just fine on my system so it doesn't really affect me.

Thx for the explaination, RW. I lack a second monitor to do the testing you describe, so I can't do any of the tests you describe on my system. As you state, though it's clear that something is funky about the way the game is running on high-end NVidia systems. . . I guess some sort of video driver-game code interaction would be the most obvious culprit.

Cheers,

Yd

[Redwolf]

You cannot just recompile code to be multithreaded.

The compiler gets about 0.001% of the job done for complex pieces of C++ software.

Changing existing codebases to be multithreaded (while still not crashing or locking up) is the area where systems-oriented programmers make a fortune or two these days.

[Pzman]

Originally posted by Redwolf:

</font><blockquote>quote:</font><hr />Originally posted by Pzman:

</font><blockquote>quote:</font><hr />

But at any rate, AIUI, BFC has already tried to re-compile the code for dual core once, but it didn't work due to a problematic Micro$haft compiler. I think it's on the list to try again, but I have no idea when.

Umm, then why does task manager show CM as using both Cores (1.08)? On my system CMSF never uses more than 50% of both cores (2.2Ghz C2D), since the task is split. </font>

[Redwolf]

Most games always use 100% (of one) CPU no matter how fast the CPU is. They just run their event loop as fast as they can. If the CPU is 15 times as fast as it needs to be they still do that.

It's not like an office application that stands still waiting for input.

[Pzman]

My point is that CMSF WONT use 100% of the CPU, not even 100% of one core if I use affinity to force it to, rather it just stays around 50% and is laggy, even in the opening screen.

[Redwolf]

Oh.

In that case I'd see whether hard disabling one core (in the BIOS) fixes that.

[Pzman]

Its not a big deal since when I play with CM using both cores there is no lag, only when CMSF is using one core only. CMSF is the only game that I have seen doe this. I could try disabling one core using the BIOS, but I just find it strange that CMSF wont use full load, while COD4, Crysis and even old games like Battlefield Vietnam do.

This isn't just on my Intel systems (notebook and desktop). I've also seen this happen with AMD dual core systems as well.

[Redwolf]

This is most unusual and I think that debugging it might give a clue why so many users of high-end systems have problems with CM:SF. You might want to mail that directly to some BFC support people.

So you say when you don't bind it to a processor it uses both at 50% and doesn't lack and when it bind it to one it uses one at 50% and it lags?

I would suggest that maybe the multithreaded version of the NVidia drivers is very unhappy about something here and has the game hang around idle for extended periods of time. That also fits the observation of unexpected improvements when bumping up CPU speed as the first post suggests.

BTW, the other games have 10s of man-years of development in the engines they bought (not wrote themselves) for multithreaded support, many times the man-years than CM:SF has total.

[Pzman]

Yes, when using both cores, they both show 50%, but when using single core it seems to hover around 50% of one. I've not tested this a lot since I really don't have a need to run the game in single core mode (unless I have a virus scan or something like that happening in the background, which is where it is nice to have a dual core system). I'm going to play around with it more tonight and see if this keeps happening, if so I might send an email.

Systems I've seen this on:

2.16Ghz Core 2 Duo (MBP with Bootcamp), which means its not just Nvidia because it has a ATI x1600 card.

2.20Ghz Core 2 Duo in my current desktop, with 8800GT

AMD x2 4800+ 2.5Ghz, with 8600GT.

All systems running XP Pro SP2. That may be an issue, I've heard that SP3 for XP will have a upgraded kernel for better multi-core support so we might see improvements then.

[ April 09, 2008, 10:18 PM: Message edited by: Pzman ]

[Pzman]

Update. Looks worse than I thought, and keep in mind this is only in the main screen, I've not even tried to load a map. 22% load one single core with extreme lag. Load does reach 100% on the single core, once I get a map loaded, but extremely laggy, almost to the point that the game is unplayable.

So I exit the map (via Ctr alt del) and put the game into dual core mode, smooth as a whistle, and it is using 100% of both cores now, BFC must have improved dual core support with 1.08!

BTW, models and graphics are both set to best.

[ April 09, 2008, 10:55 PM: Message edited by: Pzman ]

[crr]

Pzman

How did you 'put the game into dual core mode' so that its using both cores 100%. This is something I would like to do.....

Can you give some easy-to-follow instructions?

Thanks

[Pzman]

I just used Task Manager and affinity settings to switch between using both cores or one core.

[SlapHappy]

I was having problems with texture redrawing, weird digital noise and momentary pauses in the game. That was on an 8600GTS with 256 MB VRAM.

I have upgraded to an 8800GT with 1GB video RAM and have not any problems with any of those issues since.

Could just be the different driver, but I doubt it.

[SlapHappy]

Just wanted to add....there ought to be some empirical way of testing to see what is bottlenecking performance on a particular machine. I would assume you would need FRAPS in combination with some other analysis type software.......

Right now I am just happy that my vid card upgrade made a huge difference.....not just in frame rate but actual QUALITY of the game graphics themselves.

[Pzman]

Yeah, the move to a 8800GT from a 8600 card is a big one.