My computer won't boot up properly. Basically whenever I start the system it starts but nothing happens, no boot screens show up, nothing at all but the system is turning over fine. I'm not getting any beep codes. I've eliminated the graphics card as the problem. Now here is the thing, if I change the memory to different slots it will work again, well mostly, but I have to keep doing this, then on occassion the system will just shut down and I'm back to square one, won't boot up no boot screens. My laist successful boot showed up a CMOS checksum error, so I put in a new CMOS battery but the system still won't boot up. I know the hard drive works as I've attached it to another system. Could the BIOS be the problem? Any ideas or suggestions?