I'd like your help to know why I can't overclock my Core 2 Duo E6400 more than 2.39 GHz (299 FSB x 8), a ridiculous 12%!
I'm pretty frustrated because I've seen reviews around the net saying people can OC they E6400s at more than 3 GHz easily and with my mobo.
My current setup:
CPU: E6400 with original air cooler
Mobo: Foxconn 975X7AB w/ latest BIOS
Power supply: Thermaltake 470W
DRR2: 2x GB Twinmos PC6400 (800 MHz) 5-5-5-18 (I know this sucks)
Sapphire X1300 512MB
2x Western Digital Raptor 150 GB in RAID0
My temps are really great (CPU at 25 C. and system at 33 C.) but the maximum stable speed I can get is 2.39 GHz (and I'm downclocking the memory speed at 4:5 - 749 MHz ).
With a memory:FSB ratio of 1:1 I just could get a stable 280 FSB.
My PCIe is set to 100 and Auto Detect PCI Clk is set to Enabled (though I'm not really sure what this means).
I tried increasing the CPU Vcore voltage, the DRAM voltage, the MCH voltage... nothing seems to work!
I don't want to reach speeds over 3 GHz, but at least 2.6/2.8 GHz!
Using the same board and CPU I managed to clock to 375FSB without any problem. Make sure you disable the CPU features such as Execute Disable bit, C1E, and Virtualization (unless you really plan to take advantage of them). Start off by setting the RAM to 400MHz, and see if that gives you any more headroom. Obviously make sure Smooth overclock is enabled. You might try increasing the PCIe speed to 105 or 110 and see if that helps at all.