Prime 95 Rev. Question

I have read a little about not using the latest Prime 95 for the Gen 4 Intel CPU's as it can generate too much heat.

What I am curious about is which version is the latest recommended for these CPU's?

Specifically, I have been running Prime95 v28.5 (Build 2) for thermal benchmarks on my i7 5820k and all of my i7 4790k builds. Should I be using a different Prime95 build for these CPU's?

I figure if a CPU cannot run under 80 C after 4 hours of Prime95 it is not a good overclock, does this sound about right?

I know you guys are the experts in this arena, where I am just a hobbyist, so I appreciate any valuable feedback on the topic.

Thanks in advance.

*Edit* I obviously mean running Small FFT...

Pre 28.5 version should generate less heat but really you can use other software too. Best is to run couple of programs for 1h+ and if you are playing games on this PC then something like 3DMark Vantage/11/13 in loop is good too. 3DMark physics tests are stressing CPU and find errors quick.
AIDA64 is good for stability testing but have to pick right tests. I generally use it for cache/memory tests.
XTU stability test base on Prime95 and is also good but for some reason benchmark finds errors much faster than long stability test.

Post so I can find this thread for Woomack's recommendations later...

BTW, are those 3DMark programs free?

I feel it all depends on your usage. If you just want to game and surf with some moderate use then Aida64 is good or similar stress tests but if you plan on running F@H or some other distributed computing software/ video editing etc. that will really work a CPU then P95 is a good one to run. Here's my experience http://www.overclockers.com/forums/showthread.php/741487-i7-4770k-IMC-is-Aida64-enough

Thanks Woomack and Johan, that was a good read.

I typically run f@h 24/7 when I am not using the machine for gaming or work.

My normal process is P95 4hrs, once it is stable there I put it on f@h overnight. If that passes I play the toughest games I own on max settings for a few hours (running through the most crowded areas in Assasins Creed Unity seems to pick up some instabilities that make it through the first tests for some reason) then 3DMark once it passes all the rest. Nine times out of ten by the time I get to 3DMark the CPU is stable under everything else I throw at it.

The second rig in my signature was running a quickie OC and I am just now dialing it in for custom voltages.

@4.6 GHz it is in the f@h stage right now. It passed P95 small FFT at 1.14v and temps right at 73 C under an NH-D14. However, f@h blue screened it in less than 30 sec. Had to pump it up to 1.16v to make f@h happy (still only 12 hours in, so we will see), but I did get bored and played some games for a few hours so that part is out of the way.

The reason for my original post is that P95 is running temps into the mid 80's with 1.16v. I don't like seeing those kinds of temps, so I stopped it at 3hrs 27min. Under f@h I am seeing a max of 67C (ambient temp is 22.5 C). Was kinda hoping I had the wrong version of P95 lol, but figured the Noctua is probably just not up to the task (the case it is in has very poor airflow).

I might look into getting AIDA as well, it's kind of a matter of time/learnig curve right now.

Thanks again for your time.

prime 28.5 temps during small ffts on 4790k will run very hot, because of fma/avx, small ffts are 20C higher than large ffts. The power draw and core temps of prime 28.5 during small ffts will be roughly the same as linx (with most recent linpack libraries). Many cant run prime 28.5 small ffts at stock on 4790k without hitting 100C (those on air with high stock vids, ie 1.25ish). Even on water I was hitting 98C with prime 28.5, and 97C with linx at 1.28vcore. After delidding, then 22C lower temps.

Prime 27.9 (without fma/full avx use) will have 10C lower temps, and most with 4790k use that version... run blend (will include small ffts). Most that run prime 28.5 will delid first. Though at 1.16v temps of 80C arent that bad, but above 1.25 and temps will get very hot regardless of cooling.

I was understanding to be this for PRIME95!!

Do NOT use any Prime95 versions later than 26.6. Here's why:

Core i 2nd, 3rd and 4th Generation CPU's have AVX (Advanced Vector Extension) instruction sets. Recent versions of Prime95 run AVX code on the Floating Point Unit (FPU) math coprocessor, which produces unrealistically high temperatures. The FPU test in the software utility AIDA64 shows the same results.

Prime95 v26.6 produces temperatures on 3rd and 4th Generation processors more consistent with 2nd Generation, which also have AVX instructions, but do not suffer from thermal extremes due to having a soldered Integrated Heat Spreader and a 35% larger Die.

RGE whats your opinion on the above please thanks!

Ajay.

Thank you to rge and Ajay57. Thank you both very much for the clarification.

I downloaded both of your recommended versions of Prime95 and will test with each for comparison purposes.

Version 26.6 will require less vcore, and also runs cooler than 27.9 since 26.6 has no avx. At your vcore your temps will likely be ok with either. But Ajay is correct in that once you get to higher vcore/overclock, even 27.9 will be too hot once you hit small ffts (even via blend) unless delidded.