I ran 2x512 sticks at dual speed at CAS2 for 5 months with no problems now i have sold that ram i have upgraded to 2x1gig sticks of the same spec (corsair pc3200 cas2) and i tried memtest straight away, without mucking about with my ram timings, and i can't run the full test without getting errors though if i change the CAS to 2.5 i can run the test with no errors. Is my ram faulty? It is designed to run at CAS2 but cannot do it yet my older ram ran at CAS2 with no problems at all.