Hello I have been reading here, delivered my PC to support, read countless of tech forums and asked around to all my friends, but I still wont get things to work. I started very long ago, that my PC sometimes did not boot, the screen just stayed black. I can hear all the fans starting, some beeps from the motherboard and some red lights that are shining on my graphic card. When I do get the PC started I can get different BSoD. PC is totaly unable to start now and the screen always flashes so quickly that I can't always see what BSoD it is. My hardware sounds: Asus m4n 78 Pro motherboard /v American Megatrends bios, uppdated. 2x Corsair Value pack 677mhz 2gb ram ( 4gb total) 1x AMT Athlon 64 AM2 4200+ 2.2 ghz CPU ( I think i got it right ) 1x 750 Watt Corsair Power Supply 1x XFX Ati Radeon 4870 HD, XXX ultimate edition, factory overclocked (1gb) 1x WD 250g harddrive ( dont know more, sticker is gone ) Graphic card, RAM, PSU and CPU have all been tested in another computer. Also ran a memtest for 24 hours which told me it allwas fine. My computer casing have USB and Sound ports in front which are NOT connected, I don't have any Webcams, microphones or anything installed. Just the uppdated drivers for the motherboard, graphic card and sound driver ( Via HD audio Device, intergrated soundcard in themotherboard ). I have a PnP usb mouse and a ps2 keyboard. I have gotten both the IRQL_NOT_LESS_OR_EQUAL bsod, BAD_POOL_CALLER, BAD_POOL_HEADER and MEMORY_MANAGEMENT. What strikes me is that every piece on my PC is less than 3months, except the HD and CPU which is a few years old. Now to more explaining. When the PC starts it runs fine ( Tempratures around 40-55celcius). I can browse the internett, play flash games and stuff. But if I start a fullscreen game like WoW, CoD, Bad Company 2 or browse a lot of websites at the same time on google chrome it will crash. I've tested to reinstall windows, it is fresh, + drivers and + WoW. I have tried to uninstall drivers and reinstall ( IRQL BSoD), I bought new psu when I got MEMORY_MANAGEMENT and I bought new Ram as well. What puzzles me is that when I turned my PC in to the computershop where I bought it and bought the new hardware they could not find any errors on it. I told then how it happened, when it happened and gave them all driver CDs, both my Vista and Xp DVDs as well. The BSoDs have happened both on Xp and Vista, and also during installing Vista. All operating systems are 32bit but they told me at the shop that if I remove 1 piece of RAM so that it is less than 3.x ram it goes fine, which I did. But I still get a BSoD when installing them now.That is when I can get to the Windows installing part. Mostly screen just stays black and nothing happens.