I've asked this before but did not get a actual answer.
Problem: Booting up the pc will result in some kind of loop, no bios screen shown, just a black screen, sometimes it breaks through and starts up XP with no problem.
What I've tried:
-Replacing the memory, booting up with 1 stick, memtest86+ fully passed
-Using diffrent Harddisks, tested them with software from Seagate ( Seatools ), using no HD at all.
-Replacing / using no Graphics Card. Used my onboard ( Ati 3200 ), went from the HD2900XT to the HD4770.
-Grounding my pc, did not make a diffrence.
-Disconnect any optical drive; no result.
-Replaced the PSU, no diffrence.
Combinations of these did not make any diffrence too.
So my guess is that the CPU is broken, but how am I going to prove this? I've had some problems installing Windows XP, while unpacking the SP3 rip the bios speaker made an endless beep for like 1 min and then it stopped and everything worked fine again. People suggest this was a cpu overheat, but when I'm gaming there's no such problem. Prime95 however made it go to 72 'C, which is quite hot I think. I'm using a stockcooler and I never Overclocked my cpu.
Problem is that I need to prove that my cpu is broken to the shop, like they said before " A cpu hardly breaks, it's more likely the motherboard or the bios version causing it ". I haven't tried bios flashing yet, horrible experience with it.
HDD's : Samsung Spinpoint ( Main + Windows XP installation ), Seagate 500GB something
GFX Card(s): Ati HD4770, Ati HD2900XT, Ati onboard HD3200
PSU: SweeX 650 watt
Optical Drive(s): DVD Player from LiteOn
Cooling: Totaly fine, 2 Case Fans
USB devices: Mouse and Keyboard, external HD of 40 GB ( Old pata drive, not used while booting )
Expansion Cards: D-Link Wireless 520+
Others: Speakers, CRT screen using DVI->VGA, Unconnected Floppy Drive
You want to get that bios flashed also before switching off yes. Nothing is more annoying that trying to flash a bios without a floppy drive so I'd connect that and also copy the .bin file to a floppy if I were you.
Save yourself a lot of hassle and try to get that bios working before switching off though.