[SOLVED] CPU speed dropping when stress tested.


May 19, 2016
Recently I upgraded my SLI GTX 670's for a GTX 970, to avoid it being bottlenecked, today I went out and bought an i5 2500k to swap it out for my i5 2500 to overclock it. My plans were to run 4.5Ghz since theres plenty OC guides for i5 2500k at 4.5Ghz and I don't think I will need more speed but I wanted to see if I can hit 5Ghz as a test since people claim 10% of i5 2500k were able to hit it. The CPU does hit 4.5Ghz but when I change the ratio to 50 or 51, it doesn't get near it, after booting and opening task manager, I can see the CPU sitting at 4.68Ghz with drops from time to time to 4.5's. The worrying thing is when I start a benchmark, the speed slowly drops to 3.9Ghz and sits there until I stop it and then it will slowly climb back to 4.68Ghz. I have set the cpu voltage to 1.4V since I have a full loop and wasen't worried about temps and wanted to focus on speed. While benchmarking, the temps get up to low 70's, high 60's which I don't think would be a reason for it to drop in speed, espically right after I start a benchmark when the water had no time to heat up. I'm also strees testing it with Aida 64 and it's reporting no throttling from the CPU.

I'm haven't tested if the CPU also drops in speed when I set the speed to 4.5Ghz. I'm very new at CPU OC'ing, I know only the basics like what voltages are dangerous and what different voltages do, the only CPU OC experience I had before today was with my i5 2500 where I set the speed to 3.8Ghz and found the lowest stable cpu voltage and left it at that, even tho the turbo clock was 3.7Ghz.

My specs are:
i5 2500k
Asus Strix GTX 970 4GB OC
MSI P67A-GD55 (b3)
4x4GB HyperX Fury DDR3 RAM
Kingston 120GB SSD
Toshiba 1TB HDD
CoolerMaster GX750W Bronze
CPU cooled by CoolerMaster Nepton block, GPU with a full-cover EKWB block.


Oct 2, 2018
There are quite a few things that I suggest checking:

(1) look at your setting for intel speedstep and C-state in the BIOS. Try disabling these features (each BIOS will have different featuers and navigation. These things might be named slightly different in your mobo and at different locations)

(2) adaptive mode might vary your vcore up and down significantly too. Try override mode. Also look at your LLC (load line calibration) and see which mode you have selected for that.

(3) go into Windows and Power Options and make 100% sure that you select the High Performance plan.

(4) To determine exactly what is throttling during your stress test run, download Intel Extreme Tuning Utility (Intel XTU). Just google it. Open it side by side with your stress test. At the bottom right corner, it will highlight which part of your setup is throttling

This is just some suggestions. There may be other factors.... But good luck.

Btw, I strongly suggest an upgrade for your PSU. The one you have is a very low tier and poor quality unit, which very likely can be a contributing cause (not 100% entirely sure, but likely) to the throttling. A 750w tier 1 psu would be ideal.