The title is a bit misleading I suppose a better way to pose the question would be to ask:
Is it likely that a faulty motherboard will damage a CPU?
My situation is as follows:
I built my computer a while ago and it worked very well for a while. Recently it began freezing, usually under load, but sometimes when idle for an extended period of time. It is not repeatable, but the amount of time it takes before freezing usually reduces after each reboot.
I have eliminated all of the hardware as the issue except the CPU and motherboard. Since my brother has the same board, I can use it to determine if the motherboard or the CPU is at fault. Playing the odds I am going to assume it is the board that is faulty, what I want to know is whether or not I am safe to put my brother's CPU in my motherboard. If I put my CPU in his motherboard and it does not freeze, then I know it is not my CPU, which only leaves the motherboard. But I would be a lot more confident if I put his CPU in my motherboard to confirm. To be completely sure I would want to connect all of his hardware to my motherboard (CPU, Video Card, Hard Drive, Memory, and PSU). There is obviously some risk, but I want to know if the risk is negligible before I risk more hardware.
This sounds like a motherboard issue. You'd probably be safest using your CPU with your brother's motherboard. You could even try connecting all of your components to it, just in case.
If you've checked and all of your other hardware is functioning normally, you should also be able to try using his components with your motherboard with minimal risk. Just check on that CPU first.
The most likely case where a defective motherboard might damage a CPU is if there is something wrong with the motherboard power regulator. Your symptoms sound like this is not the case, but why take chances.
In the case of a questionable CPU, it's safer to test that CPU in a working system.
I went ahead and put my CPU in my brother's computer and it worked very well. This game me the confidence to put his CPU in my mobo, which still froze. Just to be sure I removed all unnecessary hardware for the final test and it still froze. Result: I got an RMA from ASUS.
Not sure how to change the status of this post to solved.