Core i7/X58 Overclocking Thread

[vikingboy]

Not the first time i've seen that, there are many posts with people doing 3.2ghz - 3.8ghz with 1.1v-1.2v, but i wouldn't be surprised if half of them won't go much higher without tons of extra voltage, that seems to be the way with these chips and a better quality chip really means you have more room before you hit this wall / ultra-diminishing returns.

exactly my findings with mine.....
3.6-3.8 very easy....
19*210 requires LOTS of V to stabalise (outside of TRUE cooling on airs ability co cool in a warm room)
Im going to try 20*200 and see if the slower memory timings let me get to 4ghz another way - without resorting to frying my CPU

[SteveRo]

There's no VID on i7s, right?

I would think vid=vcore=Vcc (in the table) for 1.55v max?

[SteveRo]

exactly my findings with mine.....
3.6-3.8 very easy....
19*210 requires LOTS of V to stabalise (outside of TRUE cooling on airs ability co cool in a warm room)
Im going to try 20*200 and see if the slower memory timings let me get to 4ghz another way - without resorting to frying my CPU

the 21 multi is the sweet spot (for me anyway) - can either of you boot at the 21 multi - maybe need to enable turbo to get the 21 multi?

[jcool]

That crappy IMC theory certainly holds true for my 940. I can run prime, linx etc fully stable at 23x192 (4,4Ghz) with 6x ram mult, but even the 8x is no go. Boots into Windows but freezes with an evil Bluescreen after 10-20 minutes of prime. That is running 3x2gb with the most relaxed timings and subtimings possible, and 2T. Also tried up to 1,6V VTT to no avail. Uncore speed seems fine, I am currently running 6x dram and 20x uncore mult (3,8xxGhz uncore) so it's not that. It really has a crappy IMC.
Furthermore I had no trouble running DDR3-2000 with my previous 3838A 920 with the same mobo and rams, so I can rule them out. I guess I got a good CPU for high Mhz (does 4Ghz at 1,3V) but it has the crappiest IMC ever.

Unless it will run the mem better using other CPU multipliers - anyone compared that yet? Or maybe it'll simply need more Vcore to do it, even though that is kinda unlogical to me. Penny for your thoughts guys...

[The-Fox]

In the table below I think max qpi v is vtta and vttd -

Yes, the spec claims max voltage of 1.35v to the Vtt analog or digital portions make no difference according to the spec.
According to the spec, the analog and digital domains of the QPI should be fed by the same voltage.
I wonder if different voltages to the Analog domain and digital domain of the QPI can help to achieve higher QPI clocks.

That crappy IMC theory certainly holds true for my 940. I can run prime, linx etc fully stable at 23x192 (4,4Ghz) with 6x ram mult, but even the 8x is no go. Boots into Windows but freezes with an evil Bluescreen after 10-20 minutes of prime. That is running 3x2gb with the most relaxed timings and subtimings possible, and 2T. Also tried up to 1,6V VTT to no avail. Uncore speed seems fine, I am currently running 6x dram and 20x uncore mult (3,8xxGhz uncore) so it's not that. It really has a crappy IMC.
Furthermore I had no trouble running DDR3-2000 with my previous 3838A 920 with the same mobo and rams, so I can rule them out. I guess I got a good CPU for high Mhz (does 4Ghz at 1,3V) but it has the crappiest IMC ever.

Unless it will run the mem better using other CPU multipliers - anyone compared that yet? Or maybe it'll simply need more Vcore to do it, even though that is kinda unlogical to me. Penny for your thoughts guys...

I kind of have the same issue only at different speeds.
I can run my CPU (x21 multi) with DDR 1800-1850 Mhz-> bClk 180-185Mhz with DRAM multi x10 benchable.
But it won't do even lower dram speeds at high CPU speeds, I couldn't pass 215 bClk with x21 CPU multi and x8 Dram multi which results in 1720 Mhz.
I tried to relax timings and raise QPI/VTT voltage to a high degree of 1.65v but none of this helped.
It was very frustrating as I could run higher CPU speeds (221blck x 21 CPU multi) at x6 Dram benchable.

I concluded that my IMC just can't run high DRAM speeds at high CPU speeds.

[jcool]

I kind of have the same issue only at different speeds.
I can run my CPU (x21 multi) with DDR 1800-1850 Mhz-> bClk 180-185Mhz with DRAM multi x10 benchable.
But it won't do even lower dram speeds at high CPU speeds, I couldn't pass 215 bClk with x21 CPU multi and x8 Dram multi which results in 1720 Mhz.
I tried to relax timings and raise QPI/VTT voltage to a high degree of 1.65v but none of this helped.
It was very frustrating as I could run higher CPU speeds (221blck x 21 CPU multi) at x6 Dram benchable.

I concluded that my IMC just can't run high DRAM speeds at high CPU speeds.

So you are saying that my 940 might run higher dram speeds if I go down on the clock? Might be.. I tried at stock clocks and got a no post using the 12x ram mult, after having to remove CMOS battery again I was fed up trying and just fired it up at 4,4Ghz again
I mean it's fine, I don't really need more bandwidth than Tri-Channel DDR3 at 1200Mhz gives, but I feel kinda stupid running 2000Mhz Diablos in there while a cheap-ass set of 1333 whould do just fine

[SteveRo]

That crappy IMC theory certainly holds true for my 940. I can run prime, linx etc fully stable at 23x192 (4,4Ghz) with 6x ram mult, but even the 8x is no go. Boots into Windows but freezes with an evil Bluescreen after 10-20 minutes of prime. That is running 3x2gb with the most relaxed timings and subtimings possible, and 2T. Also tried up to 1,6V VTT to no avail. Uncore speed seems fine, I am currently running 6x dram and 20x uncore mult (3,8xxGhz uncore) so it's not that. It really has a crappy IMC.
Furthermore I had no trouble running DDR3-2000 with my previous 3838A 920 with the same mobo and rams, so I can rule them out. I guess I got a good CPU for high Mhz (does 4Ghz at 1,3V) but it has the crappiest IMC ever.

Unless it will run the mem better using other CPU multipliers - anyone compared that yet? Or maybe it'll simply need more Vcore to do it, even though that is kinda unlogical to me. Penny for your thoughts guys...

I have really gotten no where with the 23 multi - 31 and 32 multi's work fairly well but the high multi's also increase the heat (higher temps) vs the x21 (seems to be the sweet spot for my proc). Hard to say what is holding back i7 - cpu vs imc. Do any of the x58 boards let you drop the qpi multi below 36? The ggbt slow setting is really too slow to be a reasonable test. Qpi multi's of 34, 32 and 30 would be very nice!

[jcool]

No... not that I'm aware of.
QPI isn't the only problem though, high BCLK takes a toll on the CPU and expecially VTT requirement, that's why I prefer the 23x mult to the 21x.

[The-Fox]

So you are saying that my 940 might run higher dram speeds if I go down on the clock? Might be.. I tried at stock clocks and got a no post using the 12x ram mult, after having to remove CMOS battery again I was fed up trying and just fired it up at 4,4Ghz again
I mean it's fine, I don't really need more bandwidth than Tri-Channel DDR3 at 1200Mhz gives, but I feel kinda stupid running 2000Mhz Diablos in there while a cheap-ass set of 1333 whould do just fine

Yahh, that is exactly my point.
Try to do the following:
Lower CPU speed to about 3.8Ghz (preferably using lower bClk and high CPU multi) and then try to increase dram speed.
If you still get no POST/unstable, try to divide if it is RAM or Uncore by running the Uncore at the same speed but DRAM at lower speed.
Keep in mind that on some cpus, higher Uncore speeds require increase in DRAM voltage.

BTW, what M/B are you using ?

[jcool]

Yahh, that is exactly my point.
Try to do the following:
Lower CPU speed to about 3.8Ghz (preferably using lower bClk and high CPU multi) and then try to increase dram speed.
If you still get no POST/unstable, try to divide if it is RAM or Uncore by running the Uncore at the same speed but DRAM at lower speed.
Keep in mind that on some cpus, higher Uncore speeds require increase in DRAM voltage.

BTW, what M/B are you using ?

Read my post again
I already ruled out Uncore, because I can run 20x uncore mult fine no problems.
Specs see sig, it's a DFI x58.

[liftedcj7on44s]

how are you guys running your uncore speeds so high? I leave my uncore ratio on auto. which sets it at the lowest ratio there is. I have tried setting it to 16x but get a no post.

[SteveRo]

No... not that I'm aware of.
QPI isn't the only problem though, high BCLK takes a toll on the CPU and expecially VTT requirement, that's why I prefer the 23x mult to the 21x.

High toll on the cpu - I don't know.
I am able to run 211 bclock all day with qpi at 1.335v (near intel max)
I thought that if I had a lower qpi multi - say 34, 32, ... I could push bclock higher.

[SteveRo]

I am trying to improve my understanding of i7 relative to cpu speed, hyper threading, vcore and the resulting temperatures.
This little experiment was executed on a 965, ggbt extreme mobo - on an open case (tech station) with water cooling (so, note – YMMV).

Starting with the cpu at default speed – 3.2ghz – the average temp under load is 46C.
Moving up to 4.0 HT on – the temp under load increases to 54-55.5C, depending on the cpu mutliplier selected.
Moving up again to 4.2 (close to the max this i7 can do) the average temps under load climb to ~75.4C.
Interesting to note then that the increase in speed from 3.2 to 4.0ghz costs ~8-9C, while the increase from 4.0 to 4.2ghz costs another 20C!

Another observation is comparing hyper threading on to hyper threading off.
At 4.2ghz, (remember - under water) the temp differences appear to be ~3C, HT off being less stressful.
Interesting that the difference was not as pronounced at 4ghz.

The last observation is that C1E seems to have more effect at higher multi/lower bclock (in lowering temps).
I suspect this might be due to C1E lowering the multi while keeping the bclock constant.
This can be seen in the realtemp 2.90 display when at idle.
That is all.

[jcool]

High toll on the cpu - I don't know.
I am able to run 211 bclock all day with qpi at 1.335v (near intel max)
I thought that if I had a lower qpi multi - say 34, 32, ... I could push bclock higher.

Looking at your sig, you are running 3x1gb of ram. Try 3x2 and you'll notice you'll need at least +0,15-0,2 VTT to run that kind of BCLK, if you can even get it stable.

[The-Fox]

Read my post again
I already ruled out Uncore, because I can run 20x uncore mult fine no problems.
Specs see sig, it's a DFI x58.

Yahh I saw you writing on the Uncore.
Missed the DFi on your sig (are you sure you didn't just add it right now ? ).
So you are telling me that you couldn't run 12x memory at stock CPU speed ?
That is really weird.

[liftedcj7on44s]

i have been running 211x19 with 1.356 vcore with qpi set to +0.150 and DRAM voltage set to 2.0v for about a week now. Never had a crash while using the PC for what i normally do. Been playing games like crazy, Backing up DVD's and never had a problem. But the instant i start Linx or Prime i get a BSOD. Guess its not enough voltage somewhere but i have fiddled and fiddled with settings and cant get anything stable. Will not even stabalize at 1.44 vcore. I have come to 2 possible causes. 1 Being as stated the OMC. My ram should be able to do DDR3-2000 but it wont. The other issue i think is HT. I am pretty much fed up with trying to get 4ghz stable. Id rather just run it at default then any other speed than 4ghz.

[Chicken Patty]

Yahh I saw you writing on the Uncore.
Missed the DFi on your sig (are you sure you didn't just add it right now ? ).
So you are telling me that you couldn't run 12x memory at stock CPU speed ?
That is really weird.

I believe the ram has to be half of the uncore, if the uncore is 16x the ram will only run at 8x. I had the same issue. I at all default settings I would set it at 10x for the ram and it'll only run 8x due to the uncore default being 16x. Please correct me if i'm wrong, but I think that is why.

[SteveRo]

I believe the ram has to be half of the uncore, if the uncore is 16x the ram will only run at 8x. I had the same issue. I at all default settings I would set it at 10x for the ram and it'll only run 8x due to the uncore default being 16x. Please correct me if i'm wrong, but I think that is why.

I think there is a +1 in there some where - something like uncore/mem multi needs to be 2x plus 1 clock?

When I am running high bclock I set multi's to qpi, uncore, mem: x36, x13, x6.

[Chicken Patty]

I think there is a +1 in there some where - something like uncore/mem multi needs to be 2x plus 1 clock?

When I am running high bclock I set multi's to qpi, uncore, mem: x36, x13, x6.

hmm, not sure where that +1 clock is though, the lowest I can set the uncore on mine is 16x.

[jcool]

Yahh I saw you writing on the Uncore.
Missed the DFi on your sig (are you sure you didn't just add it right now ? ).
So you are telling me that you couldn't run 12x memory at stock CPU speed ?
That is really weird.

Well at least not on stock VTT (which is 1,21 with the DFI), no.
And no, I didn't just change my sig, changed it last week already to i7

I believe the ram has to be half of the uncore, if the uncore is 16x the ram will only run at 8x. I had the same issue. I at all default settings I would set it at 10x for the ram and it'll only run 8x due to the uncore default being 16x. Please correct me if i'm wrong, but I think that is why.

Not quite. Uncore speed has to be AT LEAST 2x as high as dram speed, or the system will be unstable. On the DFI board, you can't select uncore lower than 2x the dram frequency, for instance.

However you can run uncore faster than 2x the dram w/o problems, like I am doing right now. Default uncore mult for 6x dram is 12x, however you can also run 6x dram 16x uncore or 6x dram 20x uncore etc. The Gigabyte has even more uncore mults available, some of them working better than others.

For general OCing, set uncore to 2x the mem speed because that setting will always work. You can always try to increase uncore later.

[Chicken Patty]

^^^thanks.

[liftedcj7on44s]

i am at 211x19
memory is at 4x and uncore is at 8x. any higher on the uncore and it will not load windows.

[SteveRo]

i am at 211x19
memory is at 4x and uncore is at 8x. any higher on the uncore and it will not load windows.

what is the lowest qpi multi that your board allows - the ggbt boards only go down to x36

[liftedcj7on44s]

the only option i have is slow or fastest.

[YukonTrooper]

the only option i have is slow or fastest.

Ouch. You need to get rid of that garbage MSI board.