Core i5 750 - trying to get past 4ghz...

mikejasonsmith

mikejasonsmith

mikejasonsmith

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85
Hi all,

Well tried my hand at overclocking this weekend and managed to get my core i5 750 to just over 4ghz on air...

Im trying to get to 4.2ghz but with no joy, the pc/bios just defaults back to standard settings.

My current settings are -

BLCK -192
MULTIPLIER X21
VTT 1.3
Vcore - 1.4

DRAM - 6

As soon as I try to tweak past my current overclock the bios just defaults back...what do i need to tweak first?? by the way my multiplier limit is 21


Anyone offer any advice...??
 
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VTT over 1.21v is going to degrade the chip according to intel.
You are using a very low vcore for 4ghz because you have majorly over-volted the uncore (vtt).
Try using 1.19-1.21vvt and 1.375v vcore as a starting point for getting stable at 4ghz.
In my experience, 4.2ghz is not worth it due to the extra voltages required just for that 200mhz speed boost, not to mention the heat.

A 4ghz i5 build is very fast and beats all of the stock i7 chips aside from the new 32nm 6 core i7.
I would spend your time getting a stable 4ghz overclock without using crazy vtt voltages.

Also your specs would be useful:)
 
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Thanks mate,

Just backed down the vtt and vcore a bit...

I really appreciate that advice - thanks.

Spec is :

core i5 @ 4ghz, 5870 2gb Crossfire and 8gb Ram, Gigabyte p55 UD4 cooled by Noctua d14...

First ever build and overclock so once again, thanks for replying, it is appreciated..
 
mikejasonsmith said:
snip
Click to expand...

What I did is find the minimum stable voltages, then bump them all up by one notch just to be sure I wasn't dancing on the very edge of stability in hot weather etc.

BS Dave said:
out of interest what sort of temps are you getting with your noctua mglover??
Click to expand...

Anywhere between 27-38 on the cores idle.
A quick blast on IBT running at max makes it hit 65c but on repeated runs it does nudge over 70c. However this program makes it run hotter than any real-world use would so I am happy with it (I have 1x120mm and 1x140mm fans on my Antec 300 as exhausts on minimum speed and no other fans).
Most importantly, the cooler is very very quiet, but then it was over £50.
 
yeah i'm running a venomous x, but have a noctua in the cupboard which i haven't tried (don't ask - i was being indecisive) the venomous twists a bit when attached and i've yet to get better than 78 degrees on load with it (on prime) i might try re-applying the AS5 one more time then give the noctua a go...
 
mikejasonsmith said:
do you think thats the problem mate?
Click to expand...

Turn off turbo and have the cpu running at 4ghz (20x200).
I have yet to hear of an i5 that won't do that. Speedstep can cause stability issues but as my 4ghz rig has no speedstep and idles in the high 20s low 30s it is no issue to me.
Speedstep is something that can be turned back o nwhen you have a stable overclock, even then I would say OC and use it for a month or so before using speedstep again.

The key to overclocking is only change 1 variable at once, as if you change more then you will be forever guessing what caused the reset/hang/bsod.
 
mikejasonsmith said:
Great thread mate,

I havent changed PCH yet....it maybe something i need to look at?

Ive just been looking at post on another site and some guy got it to 4.7ghz...unbelievable...
Click to expand...

I think that I had a bsod with it on stock but it may have been another voltage I set wrong. Basically as I was changing multiple voltages at once it was hard to pin down exactly what the problem was!
I would just leave it on stock unless you get a bsod.

Also, don't leave ANY voltages on auto!!! Your board will seriously overvolt.
 
mglover070588 said:
http://forums.overclockers.co.uk/showpost.php?p=16312201&postcount=611

These are my settings. Remember all my voltages (aside from ram) are one notch above minimum stability.
To class as stable I run IBT on max 50 times whilst prime95 is running 4 threads in the background.
Please read the entire thread from my link, it is very good and has a lot of decent info.
Click to expand...

Out of interest why do you run IBT and prime together? I mean, your CPU can't run 2 100% load apps at full speed at the same time - it will simply spend half it's time on IBT and half its time prime.

I did this by accident once as i closed prime with the x button so the threads keep running, then opened IBT. All that happens is running prime stops IBT fully stressing the CPU and vice-versa. I found temps were lower than just running IBT on its own. I think these programs are best run by themselves one after the other as intended.
 
mglover you've got me seriously worried now

the only thing i changed in my bios was the cpu voltage to 1.3...i left everything else on auto including load line calibration - this in on a P7P55D - Pro...

I can't get over how good your Noctua temps are...
 
Liampope said:
Out of interest why do you run IBT and prime together? I mean, your CPU can't run 2 100% load apps at full speed at the same time - it will simply spend half it's time on IBT and half its time prime
Click to expand...

You are right, running them together is pointless
 
Liampope: I found running both made the temps the same as just IBT myself.

gurusan said:
You are right, running them together is pointless
Click to expand...

I ran them both at the same time as I was out of the house for almost a whole day.

Prime passes easy, but IBT failed on the 25th run, so I knew I was not quite stable and continued tweaking.

BS Dave said:
mglover you've got me seriously worried now

the only thing i changed in my bios was the cpu voltage to 1.3...i left everything else on auto including load line calibration - this in on a P7P55D - Pro...

I can't get over how good your Noctua temps are...
Click to expand...

Load Line Calibration can have voltage spikes (so I was told on here) so imo leave it off. LLC off WILL mean you need more vcore to be stable though.

Your temps are high because leaving things on auto massively overvolts.
 
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so are you saying my stock motherboard settings ie auto are all super high?

Just to clarify i'm using the overclocking software supplied by asus in windows, rather i'm doing things the old fashioned way in the bios.

I mean i'm assuming they're not dynamic (motherboard is changing them as i change the cpu voltage)

I'm gonna note them down and post back later on today, but i've been edging v core back from 1.3 with load line calibration on. so far i've got 2 notches back to 1.2865 - but the load line does push it up to 1.3 when under load...

The way i looked at it was it was 6 of one (v droop) to half a dozen of another (ll cal). If it's better to plump for the 1st i'm all ears...

Temps (admitedly after tidying case innards and with side off) are now maxing at 72 which is much nicer.

As always appreciating the feedback/help. Reminds me of how helpful people were back when i first set up my dfi ultra-d (great times!!)
 
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