I'm having problems running my 4gb kit (2 Rams of 2gb) Hyperx ddr2 1066 to advertised speed and timings 5-5-5-15. This is my Hyperx version KHX8500D2K2/4G. Before I was able to run it with no problems but now my PC restart itself 3 times and after that it automatically change it to 800 speed with standard timings. The only way my PC let's me run it on 1066speed and 5-5-5-15 timings all day with no problems is if I let it first run to Window with the 800 speed an then restart it and change the speed and timing in the Bios. But if I let the PC turned off for 1 hour or more it starts making the same restarting problem as before.