Hi, Here's a bit of important background to my problem. Last year, my old motherboard, an MSI G41-P28, broke down and died (it actually served as a replacement to my much better ASUS mobo (forgot its model) a long time ago), so I replaced it with a G41M-P33. I know the mobo's not that great, but it's quite hard to find one that still supports my CPU's old socket (775 LGA, my CPU is an Intel Core 2 Quad Q9400). My GPU is an HD4870 512MB which replaced an old 4870 that died possibly due to Bitcoin mining. Anyway, I replaced the motherboard, everything else in my rig is the same, from the CPU, PSU, HDDs, optical drive, GPU, etc. Now, here's the problem. I usually play Dota 2 on my rig. At very random occassions, my FPS would quickly drop from a comfortable 45-60 fps to a terrible <10fps. If I'm lucky, I could just wait it out and after 5-10 minutes it goes back to normal, but usually I just restart Dota 2 and everything usually goes back to normal for another thirty minutes. Keep in mind that these slowdowns occur usually when almost nothing is going on in-game. Like, when I'm just running in a quiet jungle, or laning without anybody harassing me. The slowdown sometimes occurs in a clash, where everybody is fighting and throwing around spells that would obviously give FPS drops, but the frustrating part is that it occurs more regularly while nothing significant is going on. I tried playing at very low settings (even went so far as to set my resolution to 640x480 when my native monitor resolution is 1680x1050), but it still happens. Now I'm also playing Borderlands 2, and I experience the same problem. It doesn't matter if I'm playing in settings optimal to my PC (everything on high except for PhysX, which gives me 40-60fps), or really low settings (everything on low, resolution at 1024x768, steady 60+ fps). The frustrating part of it is still the same: The sudden FPS drop occurs when nothing significant is going on in-game, like walking around without even shooting anything. It usually gets fixed by restarting Borderlands 2, but it happens again after 10 or so minutes of gameplay. Now I just resort to playing on my laptop since it's so frustrating to play on my rig now. But I really don't want to let my rig go to waste since I've invested quite a lot building it and keeping it alive for about three years. Any advice and suggestions on how to fix my problem(s) are greatly appreciated. Thanks in advance. Edit: I turned on Afterburner and kept it running on a second monitor. I noticed that whenever I get the severe FPS drops, my GPU usage goes down from normal (>50%) to 0-1%. Did the GPU suddenly go ninja or something? I could really use a clue on what's really going on around here.