Question Motherboard connection (Crosshair V formula-z)

[holygaab]

Hello there!
Context : Recently interchanged my old mobo (Asus M5a97 sound card and other defects) for a Crosshair V Formula-z mobo.

Reinstalled every components as on my last setup, same connections 24 pins / 8 pins /front panels'.
But now it wont boot at all black screen , no beeps signals, but power is on and cpu/case/gpu fans and mobo lights works.

What i get is "FF" code and "CPU_led" light on.

The thing is I tried to plug in the 4 pin ez_plug molex and it booted into bios and os. But is it normal? Heard that it was normaly for additionnal gpu power... but i didnt needed on my last mobo.

Here is my rig :
-Crosshair V formula-z
-AMD Phenom ii X4 960T
-2X 4gb ram 1333mhz
-geforce GTX 580 (8pin+6pin connected)
-2X SSD 120 gb (OS on oneof them)
-HDD 1TB

Thank you all and looking out for your kind assistance.

 

[laptop-Tech]

The new motherboard could be incompatible

 

[holygaab]

The new motherboard could be incompatible

I don't see what component would be incompatible.
Socket am3+ support am3 and am3+ cpu
ddr3 - thats what i have. (yeah i know im late on upgrading

the strange thing is that it will boot bios and os seamless when i connect the 4pin ex_plug which is strange!?
But my gtx580 didn't need the extra power on my previous mobo...

I didn't plug the 4pin cpu additionnal power since i didn't need/had one on the m5a97 and i dont have 4 pin cord with my psu.

im here standing in confusion...

 

[laptop-Tech]

Im confusseled

 

[holygaab]

Im confusseled

Stay awhile and listen...
After some reading in the mobo's manual i found out that I didn't put the ram in the "recommanded dimm" which are the A2 B2 slots.
So i tried switching my RAM from A1 B1 to A2 B2 and it POSTed. Great! Might be why i got the CPU_led and FF code.

Still don't know why though when still in the A1 B1 dimm plus the ez_plug populated i got a POST.

If anyone would enlighten me on this mystery it would be cool.

But for the moment my rig is running seamlessly...

 

[laptop-Tech]

Thanks for the help