I've been having this issue for over a week, and I think I've narrowed it down to Steam somehow being part of the problem. The problem is persisting even after a completely new install (removed from programs, deleted Steam folder). Clean installing numerous drivers had made no difference. It especially makes no sense because I've encountered the issue now on two separate partitions.
Intel E8400 (3.0 ghz)
Asus P5G41T M LX
Corsair XMS 3.5GB (since it's on XP 32-bit) 240-Pin DDR3 SDRAM DDR3 1600 PC3 12800
EVGA Geforce GTX 560 Ti 1024mb
Corsair TX650W PSU
Windows XP Home 32-bit
Every couple seconds, I get a stutter. Framerate will drop from 60 or 300 (uncapped Source games) all the way down to less than 30, just for half a second, but enough for me to notice it and disrupt how smoothly the game plays. I tested it with Assassin's Creed II, Batman Arkham City, Half-Life 2, and Team Fortress 2. All of them had stutters/ framerate drops.
I tried Mirror's Edge installed from a disc, no stutters or drops. Mass Effect 3 installed through Origin, no problems either. Add Steam shortcuts to those two games, run them through Steam, same problem as the Steam games. I disabled overlay, which is not an acceptable solution, but it doesn't matter because it did nothing to stop the problem in TF2 or HL2. So, all I can see is that Steam is somehow causing the issue. You might want to say it's a GPU bottleneck issue. Except this computer has had no bottlenecking issues at all in the past 6 months. This is only a recent problem, the past two weeks at most. GPU and CPU temperatures are normal (30-40C idle, 60C under games) as well.
Intel E8400 (3.0 ghz)
Asus P5G41T M LX
Corsair XMS 3.5GB (since it's on XP 32-bit) 240-Pin DDR3 SDRAM DDR3 1600 PC3 12800
EVGA Geforce GTX 560 Ti 1024mb
Corsair TX650W PSU
Windows XP Home 32-bit
Every couple seconds, I get a stutter. Framerate will drop from 60 or 300 (uncapped Source games) all the way down to less than 30, just for half a second, but enough for me to notice it and disrupt how smoothly the game plays. I tested it with Assassin's Creed II, Batman Arkham City, Half-Life 2, and Team Fortress 2. All of them had stutters/ framerate drops.
I tried Mirror's Edge installed from a disc, no stutters or drops. Mass Effect 3 installed through Origin, no problems either. Add Steam shortcuts to those two games, run them through Steam, same problem as the Steam games. I disabled overlay, which is not an acceptable solution, but it doesn't matter because it did nothing to stop the problem in TF2 or HL2. So, all I can see is that Steam is somehow causing the issue. You might want to say it's a GPU bottleneck issue. Except this computer has had no bottlenecking issues at all in the past 6 months. This is only a recent problem, the past two weeks at most. GPU and CPU temperatures are normal (30-40C idle, 60C under games) as well.