# Core i7 5775C maximum real overclock and self defence



## Artas1984 (Apr 7, 2018)

I've been testing my Core i7 5775C to find it's real maximum performance.

My aim was to find out the maximum working frequency at which the CPU would never throttle. That includes fining the optimal bios settings and voltage too.

Let's start with the fact, that Core i7 5775C is the only Intel 8 thread desktop CPU that can reach 4 GHz at 65W TDP without any additional voltage. If anyone knows any other desktop CPU that does 4 GHz at no more than 65W, please indulge me. This is achieved by simply having turbo boost set at 4 GHz to all cores. It will not go above 4 GHz without additional voltage.

Still though, 4 GHz is not enough these days to provide ''support'' for testing powerful video cards. What we do? Add voltage to vcore, pll, and ring (if needed), and then add frequency either by raising the turbo boost multi (base clock keep to default 33X) or raise the base clock (turbo boost disabled). The problem is that this CPU has a self defense mechanism, that ignores BIOS settings and throttles frequency down whenever power requirements exceed it's written limits.

I overclocked Core i7 5775C to 4.5 GHz with 1.38 V vcore, 1.9 V PLL and 1.2 V vring. C states, EIST and thermal monitor were disabled. Still, once i loaded CB R15 and Prime95, the CPU would actually throttle real bad - to 3.7 GHz in CB R15 and to a pathetic 2.4 GHz in Prime95... 4.5 GHz was good only at idle, or on ''paper'' like we like to say...

I did not understand what causes this throttling, since i enabled the power limit from 65 W to 150 W and miliamps from 95 to 200. I figured out the CPU ignores all the bios settings, and has some kind of internal voltage or heat threshold, so i stared experimenting.

I came to the very precise point of finding that 1.31 volts is the maximum voltage at which the CPU would not throttle no-mater what frequency is set to all cores. 4.3 GHz OC at 1.31 volts crashes BSOD during stress test. 4.2 GHz OC at 1.31 volts seems to be stable and does not throttle - the cores are at 4200 MHz during the whole CB R15 run, with occasional two cores drooping to 4100 MHz for a couple of times. If i set the vcore at 1.32 volts, the clocks would drop from 4.2 to 4 GHz half of the test time. If i set the vcore at 1.35 volts, the clocks would drop from 4.2 to 3.8 GHz most of the test time. At 1.38 volts, the clocks would be at 3.6 GHz almost the whole time - you get the picture now - the more vcore, the more throttle... I have not still found what is the lowest voltage at which the CPU can run stable 4200 MHz on all cores without drooping.. But with 1.31 volts, the temps are still nice.

That means, that 4.2 GHz is the real max speed of this CPU. More are possible, but in real life you won't see them in action due to throttling. Still, 4.2 GHz overclock is not bad, considering it's base frequency is only 3.3 GHz - it's actually solid, although, come to think of it, this is not the CPU for overclocking...







An example of Core i7 5775C 4.2 GHz OC running at 1.32 vcore - occasional drops to 4.1 GHz were noticed. The CPU cooler used was a budget single tower, so better temps should be expected with a twin tower.


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## newtekie1 (Apr 7, 2018)

Artas1984 said:


> Let's start with the fact, that Core i7 5775C is the only Intel 8 thread desktop CPU that can reach 4 GHz at 65W TDP without any additional voltage. If anyone knows any other desktop CPU that does 4 GHz at no more than 65W, please indulge me. This is achieved by simply having turbo boost set at 4 GHz to all cores. It will not go above 4 GHz without additional voltage.



My 8700K 4c/8t@4GHz only uses 50w.





Though, from what I've seen with the 5775c, around 4.2GHz is about the maximum you can go and remain stable.  After that they take a stupid amount of voltage to stay stable, and you just end up hitting thermal limits of ambient cooling.


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## Assimilator (Apr 7, 2018)

The answer can be found in AnandTech's Broadwell review, to be precise this table:






The throttling is occurring because you are hitting the 150W power limit.


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## cucker tarlson (Apr 7, 2018)

You have to disable short time power limit in intel xtu, it's the only way to go around this 65w limit.
Mine can hit 4.2GHz at 1.28v, and 4.4GHz at 1.42v. I can't remember what voltage I used for 4.3GHz.


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## Zyll Goliat (Apr 7, 2018)

If you really want to see does your CPU going to


newtekie1 said:


> My 8700K 4c/8t@4GHz only uses 50w.
> 
> View attachment 99472
> 
> Though, from what I've seen with the 5775c, around 4.2GHz is about the maximum you can go and remain stable.  After that they take a stupid amount of voltage to stay stable, and you just end up hitting thermal limits of ambient cooling.


How come you have only 4c/8t on 8700k???Did you disable other 2 cores in bios or what is going on?And yeah The Core i7-8700K has a TDP of 95W, but consumes around 86W at full load,when is OC then it´s another story he can consume more power depend how good sample of CPU you have.......


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## newtekie1 (Apr 7, 2018)

Zyll Goliath said:


> How come you have only 4c/8t on 8700k???Did you disable other 2 cores in bios or what is going on?And yeah The Core i7-8700K has a TDP of 95W, but consumes around 86W at full load,when is OC then it´s another story he can consume more power depend how good sample of CPU you have.......



Yes, I disabled 2 cores, with all cores active the power consumption goes up to 70w.  But he was talking about 4 core processors, so that is what I used for a fair comparisons.


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## cucker tarlson (Apr 7, 2018)

newtekie1 said:


> Yes, I disable 2 cores, with all cores active the power consumption goes up to 70w.  But he was talking about 4 core processors, so that is what I used for a fair comparisons.


what is your tdp reading in ibt max preset ?


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## Zyll Goliat (Apr 7, 2018)

newtekie1 said:


> Yes, I disable 2 cores, with all cores active the power consumption goes up to 70w.  But he was talking about 4 core processors, so that is what I used for a fair comparisons.


Ok...cool....still it´s a bit lower power consumption for that chip so either you have golden sample so you can under V or it´s something weird....as I saw in many test´s when 8700k is OC he can consume up to 160W.....


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## Artas1984 (Apr 7, 2018)

newtekie1 said:


> My 8700K 4c/8t@4GHz only uses 50w.



Excellent. This CPU is even better than i thought.



Assimilator said:


> The throttling is occurring because you are hitting the 150W power limit.



Well i increased the power limit to 250 W, and still, at 1.35 V i get throttling.


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## cucker tarlson (Apr 7, 2018)

Lol disable it in xtu like I showed you.


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## Artas1984 (Apr 7, 2018)

cucker tarlson said:


> Lol disable it in xtu like I showed you.



Yes once the power limit had been enabled to 250 W in Intel XTU, instead of BIOS, the CPU does not throttle any more at 1.38 V. I guess it's time to overclock.
What's you max OC CT?


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## Assimilator (Apr 7, 2018)

newtekie1 said:


> Yes, I disable 2 cores



WHY.


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## Fouquin (Apr 8, 2018)

Assimilator said:


> WHY.



Reading the reply it looks to be purely for the comparison. I'm sure nobody buys an 8700K to lock down two cores, that's called a 7700K.


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## cucker tarlson (Apr 8, 2018)

Artas1984 said:


> Yes once the power limit had been enabled to 250 W in Intel XTU, instead of BIOS, the CPU does not throttle any more at 1.38 V. I guess it's time to overclock.
> What's you max OC CT?


4.4GHz, but I use 4.2GHz daily. I have L4 bumped to 2000MHz as well.


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## Artas1984 (Apr 8, 2018)

cucker tarlson said:


> 4.4GHz, but I use 4.2GHz daily. I have L4 bumped to 2000MHz as well.



So even with Intel XTU power settings, you'd think i might be able to get something extra out of this CPU, but no. With throttling being not a problem at higher voltages, i set 4.3 GHz at 1.38 vots, but it BSOD. Literally, i need over 1.4 volts just to maintain stable 4.3 GHz, so what i said earlier was correct - 4.2 GHz is the max realistic frequency, as you need to bump a whole Volt just for additional 100 MHz, and 4.4 GHz fails even at 1.45 volts for me.


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## Vayra86 (Apr 8, 2018)

Zyll Goliath said:


> If you really want to see does your CPU going to
> 
> How come you have only 4c/8t on 8700k???Did you disable other 2 cores in bios or what is going on?And yeah The Core i7-8700K has a TDP of 95W, but consumes around 86W at full load,when is OC then it´s another story he can consume more power depend how good sample of CPU you have.......



When I monitor power draw on my 8700K @ 4.8 6c/12t full stress, at 1.34v I get between 135-145W numbers. 150W is also the realistic cap for this IHS solution without a delid and its clearly the wiggle room Intel is always trying to work with.

Regardless that 5775C is a beautiful little CPU, always wanted one but I could never really justify it.



Fouquin said:


> Reading the reply it looks to be purely for the comparison. I'm sure nobody buys an 8700K to lock down two cores, that's called a 7700K.



Yeah with the 'minor' exception that a 7700K runs into the same limitations as the 8700K does, but at 4 cores instead of 6  Its a mistake to think CFL isn't a step forward other than Intel just fusing on two extra cores, there is an efficiency jump in here as well.


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## cucker tarlson (Apr 8, 2018)

Artas1984 said:


> So even with Intel XTU power settings, you'd think i might be able to get something extra out of this CPU, but no. With throttling being not a problem at higher voltages, i set 4.3 GHz at 1.38 vots, but it BSOD. Literally, i need over 1.4 volts just to maintain stable 4.3 GHz, so what i said earlier was correct - 4.2 GHz is the max realistic frequency, as you need to bump a whole Volt just for additional 100 MHz, and 4.4 GHz fails even at 1.45 volts for me.


What is your L4 running at ? check edram clock in hwinfo64.



Vayra86 said:


> Regardless that 5775C is a beautiful little CPU, always wanted one but I could never really justify it.


It's pretty beastly in games thanks to L4, once I upgraded my 4790K I felt the difference right away in watch dogs 2. It's pretty amazing it can outpefrom a 5GHz 7700K at just 4200MHz. In most other uses,however,I see it loses to devil's canyon cause of lower clockspeed. It's also pretty cool under load, I hit 60-62 in IBT max preset at 1.29v and only 70-71 at 4400MHz 1.42v, and that's on D15S with a  single fan.


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## Assimilator (Apr 8, 2018)

Artas1984 said:


> ... 4.2 GHz is the max realistic frequency,* as you need to bump a whole Volt* just for additional 100 MHz...



I think you mean "a whole .1 volt".


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## Artas1984 (Apr 9, 2018)

Assimilator said:


> I think you mean "a whole .1 volt".



Correct! A whole lotta 0.1 V.



cucker tarlson said:


> It's pretty beastly in games thanks to L4, once I upgraded my 4790K I felt the difference right away in watch dogs 2.



Nice find! Had no idea about it.


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## dj-electric (Apr 9, 2018)

I currently own both the 5775C and 4790K, and i didn't have a single case where the 5775C beat the 4790K in games, especially when both OCed (5775C @ 4.2, 4790K at 4.8).


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## Assimilator (Apr 9, 2018)

dj-electric said:


> I currently own both the 5775C and 4790K, and i didn't have a single case where the 5775C beat the 4790K in games, especially when both OCed (5775C @ 4.2, 4790K at 4.8).



Were you using the iGPU?


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## dj-electric (Apr 9, 2018)

I was talking about a dGPU comperison. Of course that in iGPU performance the 5775C blows everything else out of the water


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## Artas1984 (Aug 10, 2018)

If you disable integrated graphics, do you also disable 128 MB DDR3 L4 cache?? Is that RAM dedicated to Iris Pro 6200 graphics only or to all of the cores???


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## cucker tarlson (Aug 10, 2018)

No, l4 cache works regardless whether you enable igpu or not. It can be disabled by disabling it in bios directly. If you have a dedicated gpu it doesn't mattter, even if igpu is enabled there's nothing hooked to it, it is not using resources.


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## DeathtoGnomes (Aug 10, 2018)

So OP, was that all done with the stock cooler?


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## cucker tarlson (Aug 10, 2018)

DeathtoGnomes said:


> So OP, was that all done with the stock cooler?


Why are you asking ?


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## DeathtoGnomes (Aug 10, 2018)

cucker tarlson said:


> Why are you asking ?


why ask why?

because he didnt mention what cooling he was using at all.


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## eidairaman1 (Aug 10, 2018)

All pstates and turbo cause variance in clocks


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## MrGenius (Aug 10, 2018)

Artas1984 said:


> If anyone knows any other desktop CPU that does 4 GHz at no more than 65W, please indulge me.


3770K all cores/threads @ 4GHz w/ 1.016V core = 63.985W Max


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## Artas1984 (Aug 11, 2018)

Yo undervolted the Core i7 3770K?.. If you disable iGPU, it will eat less W, did you do it?



DeathtoGnomes said:


> So OP, was that all done with the stock cooler?



4 GHz turbo boost yes. 4.3 GHz sure as heck no. No less than 1.38 V is needed for 4.3 GHz OC.


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## MrGenius (Aug 11, 2018)

Artas1984 said:


> Yo undervolted the Core i7 3770K?.. If you disable iGPU, it will eat less W, did you do it?


Is that undervolted? I don't even know what stock voltage is TBH(I've never ran mine stock). Isn't it different for every chip? Anyway, I just set it as low as I could to run IBT with Stress Level: Maximum @ 4GHz and not crash. And yes, the iGPU is disabled.


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