Might be a silly question, but can a Sempron 145 support 4 sticks of RAM?
The motherboard is an ASRock 970 extreme4, and the BIOS will show all four sticks. But when I run either Memtest86+ (v5.01) or Memtest86 (v7.4) both only report ~6118M of RAM, i.e. about 3 sticks. I'm in the process of checking each pair separately, but I just want to check I'm not wasting my time trying to get all 4 to work! Each stick is 2GB, same brand and model.
After testing both sets separately and finding no problems, I then added the sticks one by one, and now all 4 work. 10 passes later with memtest86 and no errors. So I guess maybe one stick wasn't seated properly??