Hello, just bought a 2x1Gb Mushkin xp2-8500 kit to match my 2x1Gb Mushkin xp2-6400 kit. Both these kits separatley do 500Mhz with ease but together anything over 400Mhz is a no go, no mater what timings, voltages or memory slots I use.

So I wonder, is this a problem caused by the two slightly different types of modules or is it a problem caused by using 4 memory modules in my P35-DS4 mobo??? I dont want to buy an extra pair of XP2 8500 if the problem is mobo related.

So input from users with 4x1Gb memory above 500Mhz would be very nice.