What is the safe OC for i7 4790k? because...

[JerrWolf]

Mine is currently sitting at 4.5ghz through my mobo's "wizard tuning setup" and CPUz says the core voltage is 1.323 consistently, but the safe core voltage is supposedly 1.2v.

I think I watched a JaysTwoCents video where he said he got 4.7 or 4.8ghz on the cpu safely.
Is this a hardware problem or because how I oc'd it? I assume the later.

 

[synphul]

It can depend on the chip, some are better overclockers than others and will reach higher speeds at a given core voltage (vcore). Part of the issue is probably because of the tuning setup option. "easy" or "auto" overclocking tells the bios to use a predetermined set of values for things like the multiplier and vcore and they tend to be overly aggressive. Meaning to increase the chances that it 'works' with most chips, the multiplier isn't all that high and vcore may be higher than necessary to improve stability. Too little vcore can cause bsod and crashing so they sometimes overshoot.

A couple things with the Jays video, for one he probably manually overclocked the cpu and for another he may have also had a good clocking chip. 1.3v isn't unsafe but it's around the upper limits of what many consider safe for every day use. 1.4 is probably the upper most limit for vcore, 1.3v or under is preferable. 1.2 is safe and more or less conservative, some 4790k's default to 1.3v stock.

4.5ghz isn't that extreme of an overclock, it's only 100mhz over stock turbo out of the box (up to 300mhz more if all 4 cores are running default turbo that's built into the intel cpu's). Your best bet is to go into the bios, manually set your multiplier to 45 (x45 multiplied by the default 100mhz base clock gives you 4.5ghz). Manually set your vcore to around 1.28v and save the settings then boot into windows.

A couple of good programs to have on hand are hwinfo64 (tells you what your current vcore is and core temps), realtemp (a simple lightweight application that gives core temps in current, min and max), prime95 version 26.6 and use small fft's for steady load thermal testing, something like rog realbench or intel burn test for stress testing. Running p95 for around 10-20min should be sufficient to get an idea of temps, realbench and ibt will run through a test and tell you if it passes or fails. It may crash if you don't have enough vcore and either you can turn down the multiplier by 1 (from x45 to x44) or slightly increase the vcore by around .010v (ie if it's 1.28 try 1.29v).

The idea is to test it for stress and temperatures and if things are fine, try upping the multiplier until you reach the target speed you want and/or slowly reduce the vcore if you're at the speed you want to find the lowest stable vcore possible for that speed. Sort of rinse and repeat through the process and you may have to do so a few times.

This guide has some good info on cpu thermals, explaining ambient temperatures, max temps under stress testing etc.
http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

Here are some basic guides to help you through the process. Haswell guides apply to devil's canyon cpu's also so the basics are there.
http://linustechtips.com/main/topic/41234-intel-haswell-4670k-4770k-overclocking-guide/

http://www.overclock.net/t/1411077/haswell-overclocking-guide-with-statistics

Worst case scenario, if you get lost or feel like you've made too many changes you can't remember where you're at with settings modifications you can always clear the bios and start over. Turn off the power, unplug the power supply at the back of the pc, either use the onboard clear cmos jumper or remove the cmos coin cell battery for a couple minutes and put it back in. Plug the power back in and turn the pc back on. You'll have to reset the system clock but it will revert any changes you made to factory defaults.

 

[JerrWolf]

That was a very informative post thank you so much for the software references and provided links ontop of the information! The jays video i recall it was a manual overclock.

 

[JerrWolf]

I reverted the bios changes back to default and adjusted my fans to turbo mode instead of silent, wasn't happy with temps so that should help.
CPU-z now says core Voltage is 1.231v and Core Speed is 4397.40Mhz. This is default settings of my motherboard.
Everything seem fine?

 

[synphul]

That seems normal for stock settings yes. I think you'll have better success with even a mild manual overclock than using the motherboard's built in performance modes or auto overclock settings. It's there for people who don't want to mess with it and attempts a one size fits all approach to getting a bit more performance out. I can't really fault the motherboard manufacturers for their quick and dirty settings because not all chips are the same and they're striving for overall success rather than precise efficient settings.

Even a decent overclock can be achieved by altering the multiplier and vcore a bit without getting too far into all the details of things like load line calibration and offsets. Those are more for perfecting and fine tuning a maximum overclock and typically used by people who are seriously into it for competition or sport or people looking to squeeze out that last 100mhz from their cpu. In reality it won't be noticeable in terms of performance. Being able to reach 4.6 or 4.7ghz would give a more noticeable difference since it's 400-500mhz above stock turbo speeds when all 4 cores are active. Then you're looking at around 10-12% speed gains.

Still not earth shattering but the 4790k is the single fastest intel cpu out of the box (aside from maybe the new 6700k, but only marginally faster performance). The gains would be much more impressive if they'd left it at the same speeds as the 4790 non k like they did with the i5 4690 vs 4690k. It comes clocked 400mhz faster than the 4790 non k from the factory, had it been the same speed as the 4790 the gains overclocking to 4.7ghz would have been closer to 18-20% but they basically pushed the chip halfway there to begin with.