I bought an Intel I5 760/Asrock P55 deluxe3/G460 rig last August and have always thought that the cpu was running at an overclocked speed of 3.8 ghz. I was careful to turn off speedstep and C1E, both Intel's speed control technologies, to make sure the cpu was only running at 3.8 ghz. Indeed programs such as cpuz verified that my cpu speed was at 3.8 ghz. Since this rig was a substantial upgrade over my ancient 5 years old AMD machine, my perception of wow performance with this then new setup was that it was adequate. I reconcile my inability to have smooth gameplay at ultra setting (at least 60 fps) to not having top of the line gear (I7, G480+. etc...).
Yesterday, I noticed my windows 7 gadget that displays cpu info, All CPU Meter, was showing the frequency at 4.0 ghz. This directly contradicted info from cpuz. I then went looking for a better gadget that would produce the correct frequency. I installed Core Temp, and discovered something totally unexpected. My CPU frequency was fluctuating constantly. Most of the time it stayed around 1.5 ghz. Only when I ran a cpu-intensive program, like Prime 95, would the frequency max out at 3.8 ghz. The program was showing me that the multiplier part of the equation (CPU frequency = BCLK(base frequency) X multiplier) was constantly changing, probably due to workload. I immediately thought that Core Temp was broken, and went looking for other frequency programs. While ASROCK OC Tuner showed 3.8 ghz, RealTemp showed fluctuating frequencies like Core Temp.
I then fired up WOW to see what these two programs, Core Temp and RealTemp, showed during gameplay. To my utter surprise, at no time during tested gameplays(all except raid), did my frequency gone past 2.5 ghz.; cpu utilization never reached 100%. I began to strongly suspect that I had been running under-clocked all this time.
I dug a little deeper and found this little entry in the bios called c state tech, a setting that controls cpu energy conservation. Upon turning it off, both Core Temp and RealTemp reported solid unchanging 3.8 ghz. When I re-entered WOW, I was shocked. The difference was startling. I can now run around Origrimmar at 60+ fps at 1920/ultra. I ran a five man and fps never dipped below 60. There is a noticeable difference between gaming at 3.8 ghz vs gaming at 1.5-2.5 ghz.
I highly suggest those out there who overclock their machines and expect the absolute best fps, energy conservation be damned, to find out exactly what frequency your rig is using.
So what are the important takeaways?
1. If you want top overclocked performance, turn off speedstep, C1E and c state tech.
2. Sometimes trusted program like CPUZ lies.
3. Use Core Temp and RealTemp to find out your cpu's exact frequency in windows.