Okay, geez, where to start. So I got this new PC, it's very nice but I am at my wits end!! It started off, all games ran fine, until I got Far Cry 2. FC2 would not even CTD but just instant reboot out of nowhere after 10-30 mins of gameplay. I tried the hotfixes provided by ATI specifically for FC2 with no joy. After this COD5 started to do the same, so did EVE. I got Red Alert 3, which has now started to crash to desktop after 5 mins of gameplay. I play Fallout 3 and it was running fine, until today where it's started doing the same thing. Sometimes it just CTDs sometimes it instant reboots out of nowhere like the others. Occasionally the screen will go black for a few seconds and give me some crap about my display drivers. I've done everything, rolled back drivers from Catalyst 9.1 all the way through back to 8.6, updated my BIOS, reinstalled my mobo drivers, my audio drivers, installed "whocrashed" (to which it tells me there are no dump files) and I am 1 step away from taking a sledgehammer to my PC. I have removed the overclock settings, tried installing the drivers with no CCC, I've tried under clocking my hardware and still nothing. Each time I remove my drivers I use a driver cleaner just to make sure it's all clean before I reboot and reinstall. I've tried switching off Windows Aero, doing a multitude of supposed "fixes" that I found around the internet (too many to remember let alone list). I did a memory test at the start of vista and it tells me there are memory issues, though does not elaborate and tells me to "contact the manufacturer". All components are new and this is a custom built PC. My specs are as follows: CPU Intel Core2 Quad Q9550 (overclocked till 4 GHz) 12MB cache RAM Gigabyte GA -X48T-DQ6 Mother Board With DDR3 - 1333 Support. Patriot Viper DDR3 4GBs (2X2) DDR2-1600MHz DHX XMS2 RAM with enabled dual channel (at 1413 MHz) Graphics Card Sapphire Radeon HD4870 X2 2GBs GDDR5 RAM Overclocked by software on GPU 800MHz on RAM 1000MHz 320GB SATA2 HD OCZ Vendetta High Performance CPU Cooler Vortex RAM Cooling system 6 standard fans Epsilon PSU - 1010W Thermaltake Mozart Tx casing It's definitely not overheating as with all settings on max on my games my GPU levels out at about 65 degrees, that's if I only have the fans on 50%, at 100% they only reach 55 degrees. My CPUs level out at about 55-60 as well. PLEASE help me, I really don't know what to do anymore!