Quote Originally Posted by Biker View Post
It was unchecked / greyed so tried to force it with 4 and 8 with no success.

This does not explain how an i7 920 is detected fine but the 5570 is 1c 1t every time...

I doubt this is OS it looks like hardware / bios to me...
Right. I should have read it better, but I was tired. So, I'll try harder to help, as an excuse.

This is what I would do, except trying other BIOS as Mydog said, which would be the first thing. Go in BIOS and check if enabling/disabling HT changes anything. Then try disabling/enabling cores. Next, you can try enabling 2D Performance Booster to see if it helps, so you'll know that it's a BIOS issue.