Dunlop0078 :
Well it could be the CPU memory controller that's damaged and causing one of the channels not to work, I would say that is more likely than the mobo itself being damaged.
The i7 980x and 990x are the only 1st gen 6 cores other than xeons.
Awesome man, you are right with your suspicion. The memory channels are all working with a spare Xeon X5650, which means the i7 920 is faulty. It is not that expensive to begin with might as well just keep it. [strike]The problem with the bclk ocing however persists and annoys the hell outa me. Could this have something to do with BIOS? I remember ocing this X5650 on the same board model to 4.2 GHz (=210 MHz x20) and then retiring it in exchange for a higher multi X5675. These six core i7s are nearing the Ryzen 5 1600 in price and are way older, more power hungry by far and also without proper warranty. That is not gonna happen. So I need to find a multi unlocked Xeon or fix the problem somehow. Any ideas?[/strike]
Edit: A BIOS update fixed the bclk lock. No problem is persisting. I am happy to have made a good deal and this thread is now closed.