There's one thing you can do to verify for sure....

Remove everything off the mobo, the power-up monitoring hardware on the mobo don't need anything but the mobo itself. No CPU, no MEMORY, no etc...

The mobo should power-up, do nothing, and not shutting down. If it still shutdown, the power monitoring circuit is overly enthusiastic at its job.

I reduced my clk multiplier from 9x to 5x, the lowest it would go, but my startup issue still persists.
While I was in the BIOS I checked out the CPU voltage status and settings, and got more confused (yes, it's possible ). My CPU is an Athlon 64 3000 (Newegg # 19-103-536). It's running at 1.4 V according to the BIOS Health status, but the Newegg data says it's a 1.5V part. I would bump it up, but since AMD makes both 1.4 V and 1.5 V versions of this CPU, I'm afraid that it might really be a 1.4V part. I can always find out the voltage by checking the AMD part# on the chip, but before I yank the cooler off, is there another way to find out?
If the CPU core voltage is supposed to be 1.5V, could running it at 1.4V be the cause of my startup problem? (e.g. perhaps sucking too much current at startup?)

Gregor

Everest will give you the info: Everest

Hi Everyone,
I finally borrowed a scope and checked the power up timing on my 450W JustPC PSU, and found that it's exactly compliant with the ATX12V spec.
On the other hand, my Epox mobo is not ATX12V spec complliant. Here's why:
The ATX12V spec requires the PSU to assert Power_OK no sooner than 100 mS and no later than 500 mS after the Power_On line is activated. The 450W JustPC PSU delivers spec compliant voltages within 70 mS after Power_On, and it asserts Power_OK at 400mS after Power_On, which is well within the required timing. Here's the problem: My Epox mobo only waits 60 mS after it commands Power_On before it shuts off the PSU by removing the Power_On command. This doesn't even give the PSU time to come up to full power let alone assert Power_OK.
The Epox evidently works with some PSUs which happen to come up faster than 70 mS, but it's certainly not waiting the required 100 to 500 mS required by ATX12V. In fact, I doubt that it even looks at the Power_OK signal at all.
I hope Epox will eventually comply with the spec. It should only require a BIOS update. In the meantime, I'll just continue to get around the problem by holding down the front panel power button as I turn on the PSU power switch.
Gregor

There is no BIOS update - PERIOD. Power-Up latching circuit required inputs from Reset and Power on switches. No CPU, no BIOS, no MEM, no ETC.... It's hardwired, the CPU had not validated power to be functional.

~1/2 second is the maximum time limit allowed to be invalid and still be good enough, there's no such thing as minimum limit, the shorter the invalid power states the better.

I suggest you RMA the mobo unless you're as handy at board component level works as I am despite not having specific-schematics.

I agree that faster is better, but there is definitely a 100 mS minimum time delay specified for the Power_OK signal in the ATX12V Power Supply Design Guide, Page 19, Table 12. i.e. "100mS<T3<500mS".

I sometimes wondered how many engineers were stupid enough to actually use the minimum time for power-ups monitoring, they normally are for power-downs/ power-offs.

It is the maximum longest time invalid states are allowed upon power-downs.