My brothers computer has been having a whole bunch of weird problems lately.

From booting into windows and having a taskbar, but no desktop icons and needing to restart, to turning the computer on, walking away for a few seconds and hearing it beep repeated over and over in a never ending fast beep.

another issue was computer freezing then the monitor turning off while the computer sat there, still on but frozen w/ a black screen...

I think most of those stopped happening but now the latest problem is the computer tries to load into windows 7, gets to the splash screen that says windows and either freezes or takes 5-10 min to boot into windows and then proceeds to freeze randomly with the screen still on. freezes in games, out of games, in 1 min after turning on to 3 hours after turning on.

The only real changes to the machine lately is a new gtx 470 and I put his parts in a new case. Computer is not overheating, i think i fixed some of the older problems like the black screen freeze w/ a older gfx driver, but this new problem is being a bit of a pain.

Im testing it now w/ one stick of memory at a time. Both sticks alone pass the windows CD memory test but when together froze the test so i couldnt get a report.

From what i can tell so far is i think maybe the dual channel broke on the motherboard? ive tried different slots for the memory and still it seems when both are in there it causes the thing to freeze.

Anyone have an opinion on this?

Edit* im checking the award bios beep codes and it seems that a never ending repeating fast beep is a memory problem, while a alternating slow/fast endless beeping pattern is a CPU problem

Now while i wasnt there and cant really trust what he told me, and the code has not repeated itself for me if i had to guess i think this is pointing to a bad stick of memory.

i just tried putting the other stick back into the computer and the computer tried to do the POST memory check and froze... (this stick passed the windows CD memory test)

whats confusing me is how can the stick work sometimes and not others? the thing is being completely random and is making me think that maybe it could be something else. any input would be great.

edit2* ok i cant seem to replicate the computer randomly freezing with either stick of memory. The only thing i can say with some certainty is that one of the sticks causes the computer stop at the memory check at bootup. its supposed to count the total amount of memory and write out  "memory (2056484584848)" or w/e but it stuck at "memor" and nothing else shows up. the POST stops, the computer freezes.