win 7 help please

Hi everyone, I am having some trouble with my new install of win 7...first let me say sorry if i have posted this in the wrong area but i have seen simialar problems posted but nothing quite the same as mine...so here we go..

i am running windows 7x64 { not sure what build}
atai radeon HD 3870 Vid card
6 gig corsair ddr2 xms2 6400 800 mhz
asus p5k-E wi/fi app mobo
2 seagate barracuda sata drives 1-250 GB 2-750 GB
2-pioneer dvd r/rw
3 case fans 1-80mm and 2-120mm

ok so the problem, for some reason at no particular times my computer will restart or freeze NO BOSD this happens like constantly every half hour sometimes an hour or 2...the only critical error i get is the event 41 kernel-power and this error.. The computer has rebooted from a bugcheck.

1.I have removed all memory and added it back 1 stick at a time no difference.
2. disconnected 750gb hard drive nothing.
3.disconnected dvd drives nothing.
4.reapplied new thermal paste to cpu nothing.
5.updated all driver..vid card..mobo.
6.run windows memory test and memtest no problems found.

so finally i decided to reinstall win7 with out updating any drivers...same problems occur.
the problem seems to occur mostly when playing counter strike source but has happened when just doing some surfing.
I have my latest minidump files if someone could maybe take a look to help me narrow down the problem it would be appreciated.

yes i bought my memory as a kit i actually have 8 gig and leaving 1 of them out of dimm3 seemed to help so i just been running 6 gb for now but the Hl2 engine is the one i need the most lol i am a server admin and kinda need to be in the game plus i love to play. could the memory error be some kinda setting in windows its self? cause as i stated i took all the ram out and started replacing them 1 at a time then i would go into game and test.
ok well i thank you all for the speedy reply..i will go through all my memory again and see if i get one stick that errors...is there any idea why hl2.exe would be having a problem? will report back soon with results. thanks again all.

yeah i tried that..ive reinstalled hl2 like 3 or 4 times..i recently switched up all my ram everything seems ok untill i get the last stick in { and doesnt matter which stick just the last one} so i would be somewhat ok at 6 gb but when i add the last 2 gb everything goes to hell alot faster then if i had only 6gb....this is very strange...ive also gone thru my bios and bumped my voltages up a notch as someone else suggested in another post but no good. could it be a windows problem? i was running xp 64bit on this machine and never had this problem until i went to win 7 x64.
anyways thanks for all the help and suggestions..if i come up with a solution i will post. thanks again...any new suggestions are welcome LaterZ

hey guys is it possible my memory controller driver is bad or corrupt in some way? cause as i said i can use any of the four dimms just not all four at the same time... and all my sticks of ram work as long as i only use 3 in any slot doesnt matter the slot as long as i only use 3 sticks and leave one slot open.