When Does Thermal Throttling Not Matter?
Dealing with a bit of a conundrum and was hopeful that you could help me. I recently started overclocking my i5-3570K on a Gigabyte ga-z77-hd3 and had been struggling to get not only get the cpu stable, but dealing with a persistent down-clocking issues under load. Currently I'm clocked to 4.4 ghz with a vcore of 1.19, and when I would watch HWInfo during IBT or Prime95 v29.4 the clock speed would constantly fluctuate between 4.4 and 1.6, despite the temps only hitting mid 80's in Prime and 90 in IBT. I started doing some reading and asking around and it seemed that it was probable I was experiencing VRM throttling since both of those programs use AVX which can be brutal and my board appears to have ****ty VRM's. It's a 4+1 I believe and half of the mosfets don't even have a heatsink. What was odd though, is that while HWinfo would show the downclocking, all of the "is throttling occurring" senesor showed 'no". After reading online I went ahead and downloaded Intel Extreme Tuning Utility to see if it could shed some extra light into what was going on. I've been running a serious of tests and experiments all day today and I think it has definitely been helpful. For these test I also downloaded the newest version of Prime 95 so I could easily toggle AVX off.
I realize most people like to run most of these tests longer but I was trying to get in as many substantial tests in one day as possible. All tests were finished with no BSOD's, crashes, WHEA 19 logs or errors as reported by the software. I used IETU to monitor CPU package temp, CPU utilization max and individual core frequencies as well as thermal throttling "yes/no". Here is what I found:
Prime 95 with AVX off
I ran 2-2.5 hour tests each of Smallest FFT's, Small FFT's and Large FFT's, and during all three tests the max and individual core frequencies stayed constant the entire time. Max temps got to mid/high 70's and maybe 80 or 81 on small fft's.
I used the quick cpu benchmark, and it took a little over an hour to render both images. Similar to Prime 95 w/o AVX, frequencies stayed constant, temps stayed in the 70's and no throttling.
Ran a 30 minute minute stress test at 8gb memory (I have 16) and same results as above.
Intel Burn Test
Performed 10 runs at standard, got a few runs in before I started seeing CPU frequencies drop with a corresponding thermal throttling spike. Followed up with 5 runs at very high and didn't even complete my first run before throttling started. Those 5 runs looked like an EKG with all of the spiked lines. Time to complete the runs also increased as first run took abut 73 seconds and last about 84. In both cases it seemed like the throttling started occurring when the CPU package temperature hit around 85+ degrees. Max temps got up to about 91.
Prime 95 with AVX on
For these I ran both Smallest and Small FFT's for 15-20 minutes and it didn't take very long for throttling to occur again, literally I think it was a matter of minutes. Temps during these got up to about 86 at the highest. I've been currently running a blended test for the past hour and it goes through cycles of no throttling with temps in the 70's and then temps hitting the 80's and throttling occurring followed by another decent way of no throttling. I guess this would make sense since blended would be composed of the hard hitting and softer FFT modes. I attached examples of what the graph looks like during the blend mode when it's throttling and not throttling.
So the question is where do I go from here? While I would like to run maybe a 12 hour stress test to confirm 100%, it does appear my system is fairly stable minus the throttling of course. When someone first mentioned it could be vrm throttling I bought some heatsinks to place on the mosfets but haven't used them yet. I can certainly do so if it would help, but I also wonder what is the point? If throttling only occurs above 85 and if I'm able to keep the system below that then wouldn't I be fine? Also can it be caused not just by high temps but high temps derived from AVX? I don't recall completely, and will test tonight, but I feel like when I was playing Battlefront 2 under a higher clock I was trying to get stable the temps would hit in that mid 80's range and there was no throttling. I really only game, browse the internet, with the extremely rare twitch streaming and photo editing in photoshop. So if it's just AVX wouldn't I be safe there too?
I appreciate any thoughts and feedback as this has been driving me insane for a while now.