An i5/i7 overclocking theory.

[Toothless]

Okay so I was thinking about this for a time and wanted a better answer than what liters of diet mountain dew can give me.

I have an i7 that run at 4.6ghz on 1.325v and it runs well, however I notice that i5's run/can run with less voltage and the only real difference between the two chips is HT.

Theoretically, I should be able to shut off my HT, and either crank the clocks up or drop the voltage to what an i5 can run at.

Am I missing something here?

 

[dorsetknob]

HT will cause the CPU to draw more power but for CPU voltage tolerance that is up to the Silicon chip lottery Draw Disabling HT may allow you to raise the Ghz or Not
It all depends on the Silicon Chip GOD and if you worship him the right way
Nothing is guaranteed in life except Taxes and Death

 

[Toothless]

But the thing is how much of a difference could I be looking at?

 

[GhostRyder]

But the thing is how much of a difference could I be looking at?

A very small amount less voltage required. I don't think you will hit much higher clocks without HT than you are now at similar voltages. Its just luck of the draw... You could try with it off and see what happens, but you would probably only lower power consumption by a small amount under loads as the most benefit.

I have played with my 5930K with HT off and it really did not give me anymore headroom or better voltages.

 

[cadaveca]

Never had disabling HT make any difference at all, in any way. Well, it did make performance less, and power draw slightly less. No difference in max clocks, or voltage needed,

 

[Toothless]

Okay, thanks guys!

 

[Mussels]

the extra cache is involved too and could be related to the volts and heat situation.

you'll get less heat, if you can get 15%+ higher clocks then my i5 vs i7 testing says you'll end up faster overall.

 

[trog100]

my 4790K runs 4.6 at 1.27 and 4.7 at 1.32.. HT on

turning off HT makes a huge temp difference.. 4 threads as opposed 8.. but only with things that use all the threads and i dont think its just temps that control the clock speed..

i would not turn HT off.. turning an I7 into an I5 dosnt make much sense to me..

trog

 

[Toothless]

the extra cache is involved too and could be related to the volts and heat situation.

you'll get less heat, if you can get 15%+ higher clocks then my i5 vs i7 testing says you'll end up faster overall.

I'm actually limited by voltage, not thermals.

 

[cdawall]

Then add more voltage

 

[Toothless]

Then add more voltage

I'm not going over 1.35v. I would need 1.4v 24/7 for higher clocks.

 

[Mussels]

I'm not going over 1.35v. I would need 1.4v 24/7 for higher clocks.

then your problem is not voltage, it's that you need a pair of these

seriously, give it a shot and see if disabling HT helps. otherwise you might just be at your limit for that chip.

 

[jaggerwild]

1.4v Smmh

 

[cdawall]

I'm not going over 1.35v. I would need 1.4v 24/7 for higher clocks.

Why are you not going over 1.4

 

[Toothless]

Why are you not going over 1.4

Safety reasons unless you can prove that 1.4v 24/7 is safe for Haswell.

 

[cdawall]

Prove it's not? Lol

 

[cadaveca]

Prove it's not? Lol

I have some dead chips that say its not. 1.35V recommend max for 24/7 use, unless you know how to tweak other voltages properly (VInput, AIO, DIO, VCCSA). No temp sensors on those regions, vInput can be deadly quick, and motherboards like to automatically scale it up past the "safe zone"

Skylake, up to 1.42V recommended by the board makers.

 

[Schmuckley]

Nothing is safe for Haswell...or the newer stuff.
I personally have had 4 Haswell chips fail with daily clocks.
It's like..almost inevitable.

rape it til it dies..then RMA.

 

[cdawall]

I have some dead chips that say its not. 1.35V recommend max for 24/7 use, unless you know how to tweak other voltages properly (VInput, AIO, DIO, VCCSA). No temp sensors on those regions, vInput can be deadly quick, and motherboards like to automatically scale it up past the "safe zone"

Skylake, up to 1.42V recommended by the board makers.

Not my fault if he doesn't know how to tweak his cpu. Vcore is usable over 1.35v everything just depends on your decision of longevity.

 

[cadaveca]

Not my fault if he doesn't know how to tweak his cpu. Vcore is usable over 1.35v everything just depends on your decision of longevity.

I always play it safe with recommendations. I want to be sure that I am not recommending anything that could be problematic, because you never know who may read what you write and take it seriously when it comes to OC. With Skylake, however, board makers were pretty clear that anything over 1.42 causes degradation. It's even written on the label of one of my ES chips by the board maker who supplied to make sure I wouldn't forget.

 

[Mussels]

a lot of people said my CPU was good to 1.5V based on 'intels specs' but people found out that was incorrect after heaps died, higher than 1.4V.

Thats why i'm at 4.7Ghz and not 5Ghz now.

 

[bonehead123]

must be luck of the draw as others have said, 'cause I set-up a 4790k at 4.8 w/1.45xxxv in my nephew's rig early last year, and it is still cranking along to this day neveranottaproblemo

 

[Mussels]

must be luck of the draw as others have said, 'cause I set-up a 4790k at 4.8 w/1.45xxxv in my nephew's rig early last year, and it is still cranking along to this day neveranottaproblemo

a quality board + PSU could definitely make a difference too.

 

[trog100]

4.6 seems the 24/7 voltage sweet spot for these chips.. mine does 4.6 at 1.27.. it needs 1.132 to be stable at 4.7..

i have stopped short at 4.7.. the pretty much unnoticeable performance gain from an extra 100 mhz dosnt make any sense for daily running..

to be honest 4.5 is the real sweet spot.. mine does that at 1.2..

i have five profiles set in my bios.. 4.2.. 4.4.. 4.5.. 4.6 and 4.7.. without running benchmarks its impossible to tell what setting my machine is running at performance wise.. there is a good 20 C maybe 25 C temperature difference over the speed range though..

i am pretty sure my chip would manage 4.8 without frying.. but 4.8 aint high enough for the benching game so i play safe and dont bother with it..


trog

 

[RejZoR]

It seems my Core i7 5820K isn't all that high of a clocker. It can't do 4.6 GHz and above at any voltage, not even at 1.35V. However, it achieves stable 4.5 GHz at ridiculous 1.15V! Which in a way makes me happy as well. 4.5 GHz on 6 cores is still quite a brute

So, only thing that remained for me to do is ramp up cache clock, currently testing 3.8 GHz (3 GHz stock) and lowering RAM timings.