Asus p8b ws won't boot with supermicro psu

[pablocool]

Hi

I have strange problem. I use Asus P8B WS motherboard in Supermicro Chassis. By now I had Corsair 1000W PSU.
I decided to change it to PWS-920P-SQ. But Motherboard wont boot. DIAG_CPU led is always on. Of cource I connected 8 pin cpu cable.
I tested another Supermicro PSU and same result.

I tested those PSU on other motherboard and booted smoothly. P8B WS is fine as work good with Corsair PSU.

What may be the problem?
Does anyone heard about such misterious incompatibility?

 

[pablocool]

This is DIAG_VGA not DIAG_CPU. Its even more misterious. I use onboard VGA.