Gigabyte 8IRXP start itself!!!!

[LinPack]

Hi mates

My computer with a P4 1.6Ghz and GA 8IRXP mainboard suddenly died. When I plug the power cord in, it starts itself.

I removed all the expansion card, ram, even CPU, the mainboard keeps start itself again everytime i plug it into main. But it not boot, here's the symtoms:

1. Power on every time plug power on.
2. Not boot, no POST, no beeep, no video, justpower on.
3. All the power rails are ok, measured by VOM multimeter
4. VCore OK, 1.5 volt, measured at the VSEN of Intersil HIP 6302 VRM controller.
5. CPU not warmer when power on
7. When i remove the CPU, VCore no longer available, return to 0 Volt (Is it normal?)
8. It's a dual bios board, so dead bios is rare
9. All caps are visually checked OK, but i haven't replaced. Measured caps onboard, there's no short circuit, but dont know if caps are leaked

What i have done:
1. Replace the CPU
2. Replace PSU
3. Replace RAM
4. Remove and repalce everything else
5. Clear CMOS 1001 times

Still no lucks.

Please advise me what to do next, should i re-caps all or should i do some more check? I really dont know what to check next.

And the 2 bios chips are soldered, too bad!