DDR3 RAM sticks detected by Windows/CPU-Z but not by BIOS

[Luiz_5]

What is going on here guys?

Bought the CPU last week, worked fine for five days and on the saturday I disassembled it for cleaning since the PC is not in a case.
Put it back together, turned it on and POST says only 2GB detected.
Switched sticks around, both worked, both booted but DIMM1 is not detecting anything in BIOS. It doesn't even boot when DIMM0 is vacant.

"OK, cool. It went bad", I thought.
Turned PC on with the second stick still in because I forgot it and opened Windows' properties.

What the heck?!

Ran CPU-Z

"So... DIMM1 isn't bad...?"

So guys, do any of you have any idea on what is this? I searched around and read it could be broken pins in the CPU but there is nothing visibly wrong with the pins on it.
Maybe in my disassembly I damaged it?

I don't have another MoBo to test this and I'm REALLY short on money right now (college and I can't find a job, the CPU was a gift from my brother).

I might take it to a PC shop in next week and see if they can test sticks with another MoBo for me or should I use the CPU back for warranty?

Thanks in advance.

 

[Luiz_5]

It was the MoBo. Cleaned the DIMMs with isopropyl alcohol and it started working again.