hi, i have recently been trying to fix a pc that wont turn on...cannot get any life out of the system whatsoever. it is a pentium 4 3.4ghz, system using a gigabyte GA-8I848PM socket 478 motherboard, 1GB (2x512MB) pc3200 DDR400 ram, win xp home. i have verified that the power supply is good, the ram is good. i have swapped the cpu with 1 of my own pent 4 - mine is only a 3.06ghz pent 4, which uses a 533mhz FSB which is the max bus speed supported by MY socket 478 mobo. the motherboard on the pc that im trying to fix has a fsb speed of 800mhz to support the faster fsb requirements of its pent 4 3.4ghz cpu (which uses a 800mhz fsb). therefore, in theory my pent 4 3.06 533mhz fsb cpu should work in the other motherboard (ive checked that the mobo supports a 533mhz bus speed), right? however the system still doesnt start up. obviously the pent 4 3.4 wont work in MY socket 478 mobo as my mobo only supports a max fsb speed of up to 533mhz. considering i cant even get the pc to turn on, i have verfied that the system is getting the correct power, and i have tried a known-good CPU and the system still wont even turn on (let alone begin the boot process), its leading me to believe that the mobo is dead. however before i order a replacement, i was just wondering if there is anything else i could do to verify that this is in fact the cause of the issue. any help is much appreciated, sorry if the wording is a bit confusing!

"i have verified that the power supply is good" How did you do that? "If my answers frighten you then you should cease asking scary questions" - Jules Winnfield (Samuel L. Jackson) in Pulp Fiction

i tested the power supply in another machine and it worked fine

"obviously the pent 4 3.4 wont work in MY socket 478 mobo as my mobo only supports a max fsb speed of up to 533mhz" It *might* work. Rather than 3.4GHz (17 x 200), it would run at 2.67GHz (17 x 133). "If my answers frighten you then you should cease asking scary questions" - Jules Winnfield (Samuel L. Jackson) in Pulp Fiction

yeh i tried the 3.4 in my mobo, the pc turned on but wouldnt boot. would it of even turned on if the cpu was nackered?