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Per core overclocking

post #1 of 42
Thread Starter 
Is there a reason why very few people here seem to bother with per core overclocking? I find that I can get up to 4.8ghz stable on two cores even though I'm topped out at 4.5ghz for all 4 cores on my 4790K. With adaptive voltage + offset its not too difficult to dial it in such that you get just the right amount of voltage at each speed level and keep the temps reasonable.

I've got a 5830K incoming and this seems especially important for games....there's no way I'm going to be able to push 6 cores as hard as 1-2 cores, but with so many games still not using more than a few threads, I don't want to leave a few hundred MHz on the table.
post #2 of 42
It's perfectly fine and safe. Intel does this on stock CPU's anyways, so why not. It would be especially useful if one or several cores were holding all the other cores back.
    
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post #3 of 42
Thread Starter 
Quote:
Originally Posted by Ahnt View Post

It's perfectly fine and safe. Intel does this on stock CPU's anyways, so why not. It would be especially useful if one or several cores were holding all the other cores back.

Yeah, it's just a lot more work. But I'm still surprised at how often games are CPU limited on one thread, so every little bit helps.
post #4 of 42
I'm currently running with core 0@4.9 and the rest 4.8 with no problems using C states and adaptive with offset. It does take longer with stability testing but for games the are cpu bound and utilize 1 core the little extra Mhz helps.
post #5 of 42
Thread Starter 
Quote:
Originally Posted by FastEddieNYC View Post

I'm currently running with core 0@4.9 and the rest 4.8 with no problems using C states and adaptive with offset. It does take longer with stability testing but for games the are cpu bound and utilize 1 core the little extra Mhz helps.

Yeah, I really wish Intel made it a lot simpler, where you could just set the exact voltage you want at a given frequency.

As far as I can tell, the way adaptive works, the voltage you set is the voltage at the highest multiplier. Every step down the voltage goes down a bit, but by using the offset you have some control over how much further down the voltage will drop. So in my 47/47/46/45 config, I set it at 1.46V - 50mv....so at 4.7 it's 1.41, at 4.6 it's 1.325ish and at 4.5 it's 1.25ish. Problem is that 4.5 really only needs 1.2V, and I'm only at 4.5 when I'm burning all four cores so it's a lot of uneccessary heat...but if I drop the offset any lower than that, it'll crash at idle.
post #6 of 42
I had a similar problem and found that keeping the Input voltage at .7 or more over vcore and Loadline calibration at 1 for my extreme 4 lowered my vcore by a small amount. I could drop it further but my wife isn't happy when I crank up the AC to blow through my rads for 15C ambient temp in my bedroom. Women biggrin.gif
post #7 of 42
Thread Starter 
Quote:
Originally Posted by FastEddieNYC View Post

I had a similar problem and found that keeping the Input voltage at .7 or more over vcore and Loadline calibration at 1 for my extreme 4 lowered my vcore by a small amount. I could drop it further but my wife isn't happy when I crank up the AC to blow through my rads for 15C ambient temp in my bedroom. Women biggrin.gif

What does LLC do anyway? Never fully understood.
post #8 of 42
It used to be for vcore droop but with the integrated voltage regulator on Haswell processors it is used to compensate for voltage droop for cpu input voltage(VRIN).
post #9 of 42
You do not have to use adaptive for per core overclocking. Manual with cstates works. It doesnt add .100v under avx load.

Just figure out what the max stable on all core first. Then see if you can push a single core up 100mhz at the same voltage or small vcore increase.

The reason its not used much is the gains are small. Say you already at 4.5ghz on all cores. A hasell will already not bottleneck at that frequency.

Per core overclocking biggest benefit is away to lower power usage under the heavy loads.

Technically you can increase single core but the benefit will be negligible unless its a very poor clocker to begin with.
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post #10 of 42
Thread Starter 
Quote:
Originally Posted by Wirerat View Post

You do not have to use adaptive for per core overclocking. Manual with cstates works. It doesnt add .100v under avx load.

Just figure out what the max stable on all core first. Then see if you can push a single core up 100mhz at the same voltage or small vcore increase.

The reason its not used much is the gains are small. Say you already at 4.5ghz on all cores. A hasell will already not bottleneck at that frequency.

Per core overclocking biggest benefit is away to lower power usage under the heavy loads.

Technically you can increase single core but the benefit will be negligible unless its a very poor clocker to begin with.

You can get a lot more out of it by using adaptive.

If you're using manual and you set your vcore to the minimum stable voltage at 45x, it's not going to be enough for 46x. You're fine in small bursts but a poorly threaded game is guaranteed to crash. If you up the voltage to what's stable at 46x, probably like another .075V or so, you're going up from like 60C at load to like 85C at 45x...you're going to roast it if you're burning all cores for hours with a video encode or something. Give it another .075 to hit 47x and you're way into throttling territory down at 45x.

With adaptive you can just set the voltage at the higher level for the max multiplier, and it'll scale down from there. As the number of active cores increase multiplier and voltages drop accordingly, fully loading 1-2 cores at 1.40V or 4 cores at 1.25V will both put up reasonable temps in the 70s. Without adaptive you're either running way too hot at full load or sacrificing frequency headroom.

I usually use intel XTU and x265 encoding in conjuction to test it out. x265 is a really heavy but still real world AVX stress test, and XTU lets you monitor and change everything on the fly. You can control the number of cores x265 is using with task manager and setting CPU affinity, and then you can see how the voltage tracks as you load up more cores. You're probably need to set a ridiculous vcore like 1.475V and a large negative offset to get enough spread, but eventually you'll get to the point where you can't keep it stable at idle due to the negative offset, since it's not proportional. Normally your vcore drops to .7 at 800mhz or whatever, the offset pushes it down to .6 and it's just not enough even at that speed.
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