Question CPU overclock disables Crossfire

[Titanion]

When I overclock my Athlon II X4 640 to 3.5 GHz, and it was Prime95 stable all afternoon, my Crossfire is disabled.

HD 5850x2

I can't even find the 2nd card.

When I load up Windows 10 on default settings, Crossfire is working.

What bios setting could do this? CPU/GPU is async.

I thought it was power, but I put in a Corsair 750W.

It is an Asrock AM2+ motherboard. I can post the model when I get home.

Thanks

 

[dorsai]

Are you overclocking using the FSB or purely on cpu multipliers ?

 

[Titanion]

242x14.5=3509

Lowered to x4

Ram is at 803 or so and stable

Motherboard is Asrock A785GXH/128M

 

[Titanion]

I'm searching through the default settings and seeing which ones make a difference. If I take the top card out and use the bottom PCIe slot, it boots up fine overclocked. Something is messing with the Crossfire.

What settings might mess with the PCIe slots?

 

[Titanion]

Has anyone experienced this before? I am quite sure. This motherboard was meant for overclocking and crossfire.

 

[Titanion]

I am back playing with this computer. Different CPU. Found a cheap Phenem X4 955 stable at 3.8 GHz. I have two Sapphire HD 5850s.

At stock CPU speed of 3.2, Crossfire works.

When I overclock, only one video card shows up. The overclock is simple. I just pumped up the multiplier and voltages.

It must be bios related.