Overclocking our i5-2500K is pretty straightforward because we aren’t able to get performance bumps simply by increasing the system’s base clock with Sandy Bridge processors. However, we can increase the CPU multiplier and core voltages to get a sizable increase in performance. The K series LGA 1155 processors have unlocked CPU multipliers, which seem to be the preferred way to get more performance out of these cores in turbo mode too.
The Fatal1ty UEFI BIOS has all its overclocking options located in the OC Tweaker Menu, and we made the following changes before we started overclocking our i5-2500K processor using the P67 Professional:
- Left BCLK frequency at 100
- Increase CPU Ratio (The math for overclocking our i5-2500K is very simple because we just multiply the BCLK frequency (100) and the CPU Ratio (currently 45) to get the overall CPU speed (4.5GHz)
- Manually adjusted DRAM frequency to DDR3-1600
- Adjusted DRAM voltage to 1.65v
After making the changes above in the BIOS, I began incrementally increasing the CPU ratio to test how far our i5-2500K could go before it became unstable. I continued to increase the CPU ratio to 46x before I noticed severe instability issues and BSODs. After backing it down to 43x, we were able to get a stable 4.316GHz overclock. This is a pretty standard overclock for this particular chip without doing any major voltage increases or memory timing/voltage adjustments. We are more than satisfied with seeing 30 percent increase in performance over the CPU’s stock settings too.
This screenshot was taken when we achieved a 4.290GHz overclock on the Fatal1ty P67 Professional
|CPU Speed||BCLK||CPU Multiplier||DRAM Frequency||DRAM Timings||CPU Voltage|
|1635 MHz||8-8-8-24 1T||1.3v|