FPS up&down in Vista (blank project)

[beyonder]

I never noticed this problem before... I think because my FPS was so high anyway. But now its a problem because I'n running some intensive texture memory functions.

I have Vista ultimate with all the latest updates.

FPS is about 4000 on a blank project. In about 3 minutes I get a huge dip down to 500 FPS. Then after about a minute it will increase to 4000 again. This cycle goes on and on.

Its a completely blank project. Just a renderloop.

Updated my NVidia drivers. Any other ideas?

?

[uncasid]

Vista has a tendancy to suck.  There are a few things that run in the background that cause your disk to thrash, and suck up HUGE amounts of processing power.  Turn off windows desktop management (dwm.exe I think), it is a service.  Also turn off Defender and Superfetch.  Loading programs will be a little slower.

[PhonicUK]

FPS is about 4000 on a blank project. In about 3 minutes I get a huge dip down to 500 FPS. Then after about a minute it will increase to 4000 again. This cycle goes on and on.

This sounds like a thermal throttling issue.

Use CPU-Z and GPU-Z to check the clock speeds and temperatures of your CPU and GPU while your application is running.

If the clock speeds keep dropping and climbing, that means it's a hardware problem and your CPU/GPU are overheating.

I think you can safely ignore uncasids advice, seems like yet another Vista basher...

[beyonder]

darn it.

I've been debugging for 5 days trying to nail this sucker come to find out its my crappy fan.

thanks Phonic! you the man 

[beyonder]

Oops...

GPU-Z didnt work (faulty readings) which caused me to post message above. Rivatuner did however.

And as far as I can see my hardware is fine! I also disabled superfetch dwm.exe service and defender.

Still not working...

Could this be a real bug? Darn it man!

[sybixsus]

You can't test this sort of thing with a blank project, because the margins are too small. 4000 FPS is 1/4 of a millisecond and 500 FPS is 2 milliseconds. The standard timers are only accurate to the nearest millisecond, so that's 1 and 2 milliseconds. The slightest bit of system overhead, or the slightest disk read (Vista reads the hard drive constantly for some people) would cause this and more.

A more accurate time can be retrieved with QueryPerformanceCounter. I don't think TV3D uses this internally, because this is unreliable on AMD processors and will often produce inconsistent results. You may wish to use it, but always use it in conjunction with another timing method and favour the alternate delta when there are large discrepancies between the two timing methods. This is how I do timing in my game.

So, if TV3D is using QPC, and you have an AMD processor, this could be the problem. If not, then the lack of clock resolution almost certainly is. Either way, you won't get anywhere trying to make sense of this with a blank project. You need to give it something heavy duty to do and then look for significant differences. Now if you could get a really heavy duty but stable scene where nothing changes and the FPS flick back and forth between 60 and 100 for no reason, I'd be seriously inclined to believe you'd found a bug. With the tiny time margins you're using, it just doesn't tell me anything. Doesn't have to be anything fancy, just give it some seriously high poly objects to render or load an actor and duplicate it a few dozen times.

[beyonder]

Thanks sybixus. 

Yeah, I tested it with my game as well which runs at 450FPS. After 3 minutes it drops to 50 FPS. Shouldn't of neglected to mention that too...

I'm reinstalling Vista. This is what its come down to. Maybe its some damn trojan my antivirus hasnt picked up. Ya, I even unistalled Avast... thought that might be the problem.

Edit: Problem solved. Bad video card. Sorry for scaring everyone. Tried the card on my XP system. Same deal. The thing is only 4 months old. whatever... 

[uncasid]

heh, I wasn't bashing Vista.  Was just stating the facts, tell me those elements wouldn't have an effect on game performance.  I can tell you from experience that they do!