make sure they're running at 800MHz .
btw have you installed them in dual channel mode?
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just saw your sig
as you have 2 HDD's, what SMPS (PSU) [wattage] are you using?
& if you've windows XP, then does it run well?
make sure you've latest drivers/bios...
*downloadcenter.intel.com/default.aspx?iid=CorporateV3+Header_2_Support_Download