The problem is that most monitoring programs, including Intel XTU, completely ignore some CPU throttling that can slow a CPU down to a fraction of its rated speed. What the event viewer reports is also only one type of throttling that can occur.
Here's an example of my 3570K running a Super PI 1M benchmark at 4500 MHz.
I took the screen shot while the benchmark was still running and it shows that Super PI took 7.789 seconds to complete the first 19 loops. All 3 monitoring programs report that the CPU is running at 4500 MHz.
Now here's the exact same computer when the CPU is being significantly throttled internally.
CPU-Z continues to report that the CPU is running at 4500 MHz and that is true but it gives no indication that the CPU is running like a slug. Look at the Super PI times now. To run the same 19 loops, this 4500 MHz CPU has taken 32.218 seconds or more than 4 times longer than what a normal 4500 MHz CPU takes. CPU-Z does not report this type of CPU throttling.
Intel should know when one of their CPUs is being throttled but look at what the Intel Extreme Tuning Utility (XTU) reports. It claims that CPU Throttling is at 0%. That's a fail and worse than that, it now reports that the CPU is actually running faster at 4.60 GHz when it continues to only run at 4.50 GHz. Another fail. These are the 2 most used monitoring utilities and neither one of them is able to tell you when there is a serious problem with the CPU.
ThrottleStop shows that each of the 4 cores are being throttled. Chipset clock modulation should always be showing 100.0% which means the CPU is running at its full potential. Instead, ThrottleStop shows 25.0% for each core.
The reduced C0% is another sign that this CPU is sick. When running a single threaded benchmark on a quad core CPU, that should keep one core fully utilized so the expected time that a core will be in the C0 state working on this task will be a minimum of 25%. The CPU will also have to spend another small amount of time in the C0 state while working on the various Windows background tasks while the benchmark is running. The first screen shot shows C0% at 27.0% which is completely reasonable and normal. The second screen shot shows the CPU is only spending 8.2% of its time in the C0 state working which is another big red flag that this CPU is being significantly throttled. The Super PI times make that obvious.
The last thing to note is the reduced CPU core temperature. A throttled CPU runs cooler because it is sitting idle internally when it should be working.
http://www.thedigitalhq.com/downloads/Edited by unclewebb - 11/1/13 at 9:33am