Two systems, both running Xubuntu 12.04 and the phoronix-test-suite from the repository.
One system is an HP dc7100 with a 3GHz CPU and 4 x 256MB PC3200 RAM (1GB) and the other is a "whitebox" with a ASRock P4VM890 motherboard, 3GHz CPU and 2 x 1GB PC3200 RAM. The RAM in the ASRock seems to underperform compared to the RAM in the HP system. How much of a difference? (half):

HP dc7100: 2466.4 MB/s
ASRock P4VM890: 1233.19 MB/s

I checked the BIOS and noticed the auto RAM setting made the RAM run at 333MHz. Confirmed the Patriot 1GB sticks were 400MHz and set the BIOS so the machine was seeing the RAM at 400MHz. It helped, the results got a little better, around 1400 MB/s. Changing the CL rate from auto to 3 (which is the rate on the identical RAM sticks) but it really didn't help. Any suggestions?