Hi All,
Another i7 4790K owner here. My setup includes the i7 4790K processor with Noctua NH-D14 cooler on an Asus Sabertooth Z97 Mark 1 motherboard. This thread has been very helpful to me and I thought I would share my experiences below:
Idle Temps are around 26 - 27 degrees C.
Running the XTU available memory and CPU stress tests results temps close to 70 degrees C @ 4.4GHZ max turbo frequency. Prime 95 has been another story. If I do not limit my turbo boost power max, short power max, and current values, the latest version of Prime 95 (v28.5) works the CPU hard enough that it will reach close to 100 degrees C and begin to thermal throttle almost immediately (this is with the CPU running again at 4.4GHz). Prime95 v27.7 will result in the processor running close to 90 degrees C at 4.4GHz. Prime95 v26.6 results in the temps less than 75 degrees C at 4.4GHZ. Prime95 v28.5 uses FMA extensions and v27.7 uses AVX - both tax the CPU more heavily than v26.6 (which uses neither).
Like many of you above, I got around this by adjusting the turbo power max, turbo short power max, and current values. My motherboard essentially had these values set to unlimited in the BIOS by default. I ended up going with values of 128, 152, and 257 for turbo power max, turbo short power max, and current respectively. Like another Asus motherboard user above, I had to divide my target power values by 8 and put these in the BIOS (i.e. 128 became 16, and 152 became 19) - I believe this might be a bug in Asus' BIOS. Doing so now keeps the temp of the CPU around 75 degrees or better running any kind of stress test, as the Noctua cooler can dissipate a lot more heat than the stock Intel HSF (so I knew I could go above the default 88 TDP value in Intel docs before limiting power). Prime 28.5 now runs at 4.01GHz, and 27.7 at 4.2 GHz - at those levels both are hitting the 128W power limit with temps around 75 degrees. All other stress/load tests run below that power limit @ 4.4GHz with temps less than 75 degrees C. I'm generally very happy with this performance - if it helps any, my chip is of a batch that was made in Vietnam. I'm not thrilled that I had to make these manual adjustments, but might be a motherboard BIOS issue.
It is important to note that both Prime 95 28.5 and v27.7 work the CPU hard enough that it its TDP is higher than 88 Watts at stock speeds (4.0GHz). If you are using the Intel stock cooler, I recommend using an older version of Prime95 to test. I don't think the Intel stock cooler was built around FMA and AVX workloads, but please someone correct me if I'm wrong. In my opinion, at the end of the day, an i7 4790k should be able to run the Intel XTU memory and CPU stress tests close to the 88 Watt TDP at stock speeds (4.0GHz), and with reasonable temperatures, otherwise something is wrong with the cooling setup and/or CPU. It doesn't make sense that Intel would claim an 88 Watt TDP and then provide stress tests that push the CPU much beyond, especially if the stock cooler is designed around that value (I assume it is; someone please correct me if this is incorrect).
I hope this helps some of you out - thank you to everyone again who contributed to this thread, you certainly helped me.
A more detailed writeup of my experience can be found here: