Determining the lowest stable voltage on i7 4790k

[Ellis_D]

I just recently bought an i7 4790k and I'm having issues with keeping this thing cool. I've tried three different cooling methods (the stock cooler, Cooler Master N520 heatsink with push/pull fans and a Corsair H80i water cooler) as well as multiple methods of applying thermal paste to ensure that the cooling method is seated properly. My case also has optimum airflow with a positive-pressure environment. At this point, I'm very confident that the issue is in the CPU and no in my cooling method. I also want to mention that I've already RMAd my chip once and the first one was having similar temperature issues.

My setup is a Gigabyte z97x Gaming 7 motherboard and I'm using a 10 minute HD encode with Handbrake to test my temperatures under 100%. Other tests such as Prime95 and Intel Burn Test are pushing my temps up into the 90s and cause throttling even when I underclock this thing so my reasoning is that Handbrake is a real-world test I'll be using frequently so I'm most worried about keeping everything stable under those specific conditions.

Now as for performance, using the stock "auto" settings, my core temps were hitting 100C and throttling almost instantly under load. I then tweaked my settings around and set all 4 cores to run at the 4.4ghz turbo clock with a Core Voltage of 1.2v. This dropped the temperatures by about 10C and prevented throttling but the temperatures were still uncomfortably in the low-mid 80s. I then reduced the voltage down to 1.169v and the temperatures dropped even more to the point where I was maxing 77C. As of right now, I have all four cores clocked to 4ghz with the same 1.169v and the temps are ranging from 69C-71C under 100% load and this is where I'm comfortable keeping my temperatures.

So what I want to know is how can I determine the lowest stable voltage? Obviously, I want to maximize my clock speeds while keeping the temperatures low. Furthermore, How can I know when the voltage is too low? Would a low voltage have obvious symptoms such BSODs or throttling or would issues manifest in more obscure ways?

 

[IInuyasha74]

Hmm wow, I normally would of thought bad CPU but you did that.
Are you using good thermal paste?

Low to mid 80s sounds like a more reasonable. Under IntelBurnTest I get about 80C on my i7-3770k at 4.4Ghz and with increased power. Since your CPU is Haswell based it has the voltage regulation on the CPU also which normally makes them run hotter. I would say your temps are fine after the first adjustment you made.

If you want to lower your temps more check the PLL Overvoltage and other settings that have a big effect on voltage.

As for getting the lowest voltage possible, it works the same as overclocking. Lower the voltage, and do a test under full load for stability. You will never get the voltage so low that the idle clock speeds are unstable.

 

[Ellis_D]

I'm using Arctic Silver 5.

Also, I'm currently running OCCT to test my setup (which is currently 4.ghz with 1.06v) and it's hovering around the high 50s-low 60s. I'm currently referencing AnandTech's review of the 4790k for the results they've found (their test setup is very similar to mine) and my results are in line with theirs for the most part. when compensating for ambient temp.

I was hoping to have this thing running at 4.4ghz at least but running close to the 80s under 100% load in a typical work environment and pushing 90 with Intel burn has me worried about the life of my chip.

 

[IInuyasha74]

Are you sure it won't run at 4.4Ghz? I mean you have had substantial voltage drops so far, and may not have hit the bottom yet, you might as well see how low voltage you can get with 4.4Ghz.

 

[Ellis_D]

Possibly and I'll try for it tomorrow (currently running a stability test with OCCT. almost an hour in and everything is going swimmingly with the aforementioned temps holding stable). The one odd thing was that when testing lowering the voltage for my 4ghz clock, when I set it to 1.05, my system seized up and I had to reset the bios. I also messed with the DDR clock and set it to 1600mhz after noticing my motherboard had my RAM set at the 1333mhz default instead of the 1600mhz it's supposed to be at. I don't know if that was a fluke caused by messing with my RAM or not to be honest.

I guess I should also ask how RAM frequency plays into the voltage equation...

...

Alright, so I double checked setting the voltage at 1.05 and it worked fine with the RAM on it's default frequency. (haven't messed with that since so I don't know if that caused the instability) and I'm currently stressing 4.4ghz. I set the volt all the way down to 1.15 but as it is now, it's reporting that it's running at 1.164 (so I'm assuming that's the lowest it will go at this frequency) and the temps are running in the high 60s/low 70s so I think I found my magic number. I'll let this run for a few hours and report back later.

 

[hapkiman]

I wouldn't use Intel Burn test or Prime on DC. They're gonna hit high 90s no matter what you do short of liquid nitrogen. Try running Aida64. And which cooler did you finally settle with? I'm using an H80i on my i7 4790k and it's working exceptionally well. I did run Prime95 once and temps soared. But I'm happy staying at 4.4ghz (enhanced "locked" turbo). If I need to test stability, Aida64 does the job without frying everything. Haswell just can't handle Prime or Intel burn. They are pretty much unrealistic and not needed scenarios anyway. Just because you can't run Prime95 for several hours without hitting 100c doesn't necessarily mean you have a bad proc. Overclock checking tool is great as well. I just prefer Aida64.