after replacing my motherboard with this one:
BIOSTAR A785GE AM2+/AM3 AMD 785G Micro ATX AMD Motherboard http://www.newegg.com/Product/Product.aspx?Item=N82E16813138156
I can only use one Dimm of memory. When I put two memorys, the machine will not boot.
The memory I used is Crucial Ballistix (2 X 1GB). BL12864AA80A.8FE5 LEAD-Free w/EPP 800 MHZ 4-4-4-12 2.0V
When I enter the BIOS setup and adjust the Memory Voltage to 2.05 or 2.15 (default is 1.95),
the machine will boot and show the memory is 2GB but the screen will hang on there right before the Windows Loading screen shows(I have Ubuntu 10.04 LTS and Windows XP installed) and there is will be some vertical red lines (or line of dots) showing on the screen.
After I changed it back to one dimm, the machine then works very well.
My CPU is AMD Althon II X2 250 3.0GHz.
Also when I enter the BIOS, the memory information is shown like 5-5-5-18.(Does that mean the memory is working under performance?)
Any help/tips will be appreciated! Thank you!