Hello, before I state my problem. the current specs of the system is A64 X2 3800+ stock cpu cooler with AS5 4GBs of RAM AsRock 939DUAL-VSTA Diamond Radeon HD2900XT also stock cooler with AS5 OCZ GameXStream 700-Watt Power Supply dual 22" LCD Monitors The problem I'm having is my system would out of no where randomly lock up. The mouse freezes and the keyboard becomes non responsive. so the only way I can resolve this is resetting the computer. I recently cleaned out all the dust in the heatsinks and repplied thermal paste onto both the GPU and CPU. This however has not solved anything. I thought it could have been RAM so I replaced it with the RAMs of another system but that didnt work either. The system still randomly frooze. I don't know if it could be video card causing this problem. It should have a 6pin + an 8pin PCI-E connector connected, but since my power supply only came with 2 6-pin I have that connected. I'm not sure if that could be my problem or not. Or it could simply be overheating video card. A friend of mine told me it could be the motherboard since it only takes a 20-pin motherboard power connected as opposed to the 24-pin most boards take these day. But If I replaced the board, I dont know which board to get since there aren't many 939 boards left in the market. So my conclusion is it's either the video card or motherboard. What do you think the problem might be and what do you think I should do to resolve this issue. I'm getting tired of it randomly freezing. >.< any help would be great! Oh yea. my system is not overclocked, everything is running stock speed and im currently using catalyst 8.4. I also have a IDE Controller Card installed and a X-Fi SoundCard as well as a Linksys WiFi Card. and if this matters. im also running Vista Ultimate 32-bit edition.