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i5 750 @ 4 GHz Any tips ?

Soldato
Joined
17 Aug 2009
Posts
10,712
Some whacky low voltage hopes for 4GHz I'm seeing.

I've just done 20 passes of High on IBT and 1.35 wasn't enough, fails after about 6 passes.

1.35626V gave a clean run.

My i5 750 isn't on a UD5, it's on a GENE III but my settings might help anyway.

CPU: 750 @ 200x20 - Speedstep enabled - Turbo cannot be enabled unless multi is on auto
RAM: 4GB GSkill 1600MHz 7-7-7-24 2T

CPU Voltage: 1.35625V
CPU PLL: 1.80V
RAM Voltage: 1.60325V
IMC: 1.20575V

XMP profile was enabled, CPU voltage was fixed to 1.35625, CPU PLL was fixed to 1.80, DRAM fixed to 1.60325 and IMC to 1.20575.

Everything else is left on automatic or what XMP set it to.
 
Joined
5 Aug 2006
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Location
Derbyshire
Some whacky low voltage hopes for 4GHz I'm seeing.

I've just done 20 passes of High on IBT and 1.35 wasn't enough, fails after about 6 passes.

1.35626V gave a clean run.

My i5 750 isn't on a UD5, it's on a GENE III but my settings might help anyway.

CPU: 750 @ 200x20 - Speedstep enabled - Turbo cannot be enabled unless multi is on auto
RAM: 4GB GSkill 1600MHz 7-7-7-24 2T

CPU Voltage: 1.35625V
CPU PLL: 1.80V
RAM Voltage: 1.60325V
IMC: 1.20575V

XMP profile was enabled, CPU voltage was fixed to 1.35625, CPU PLL was fixed to 1.80, DRAM fixed to 1.60325 and IMC to 1.20575.

Everything else is left on automatic or what XMP set it to.

I think that without LLL I would be on about that voltage for the cpu. What is your reasoning behind not using it?
I have never used speedstep on an overclocked cpu, does it cause any instability issues?
btw thanks for the input:)
 
Associate
Joined
26 Feb 2010
Posts
34
Still running prime 95 for an hour now, no errors

200x20 4ghz at 1.25 volts. max temps 64 degrees.

Ram is on 8-8-824 and 1.64 volts

rest on auto

Standard
perfect
 
Soldato
Joined
16 Oct 2009
Posts
8,917
Location
Essex
Does auto mean your mobo ups the uncore voltage of your CPU automatically? If so, try setting it to max recommended by Intel - 1.21 V. If it does crash with this, your overclock is either ****** up or you risk damaging your CPU.
 
Soldato
Joined
17 Aug 2009
Posts
10,712
I think that without LLL I would be on about that voltage for the cpu. What is your reasoning behind not using it?
It's on automatic and the CPU voltage does increase under load which means it is being used.
I have never used speedstep on an overclocked cpu, does it cause any instability issues?
Nope. It changes the multi only if it's needed. So on idle it's on 9x which is 1.8ghz. When the CPU needs to do some work the multi will flicker up and down from 9x to 20x and any step in between.

When doing stress testing the multi will be mostly bang on 20x for the full 4ghz but even then it will bounce down to a lower multi if like IBT the program takes breaks between loading up the CPU in tests.

Lowers power consumption, doesn't lower performance, what's there to lose?
 
Last edited:
Joined
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It's on automatic and the CPU voltage does increase under load which means it is being used.
Nope. It changes the multi only if it's needed. So on idle it's on 9x which is 1.8ghz. When the CPU needs to do some work the multi will flicker up and down from 9x to 20x and any step in between.

When doing stress testing the multi will be mostly bang on 20x for the full 4ghz but even then it will bounce down to a lower multi if like IBT the program takes breaks between loading up the CPU in tests.

Lowers power consumption, doesn't lower performance, what's there to lose?

Nothing to lose at all as long as it is stable:)
Speedstep isn't exactly new so I assume it is fairly good by now.
 
Associate
OP
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30 Dec 2008
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SCOTLAND
Stuck LLC to [Standard] and still (Short term testing) stable @ 4 GHz.

Lower volts (1.28v ~ 1.3v) means lower temps, Average around mid sixties in a heated room.

Cheers for that wee tip, Most reviews i read said to use LLC.
 
Soldato
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8,917
Location
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I gave up. Voltage under-shoots and over-shoots are for too great to give me a high overclock with reasonable voltages. Giving a try with 1.7v BIOS in a minute.
 
Associate
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26 Feb 2010
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34
The auto means on all voltages except ram and vcore.

My cpu things disabled, the multiplier is fixed.

4.ghz without dropping fron multi 20 to 9
 
Associate
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26 Feb 2010
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Had prime95 running all night with no errors. :cool:

This are the settings.

200X20 = 4ghz @ 1.275 vcore
Ram 1.64 volts
Rest of voltages on auto.

This gave me a max temp of 67 on one core, the others were lower.

I will try to lower the voltages a bit until it fails.

Will report back
 
Soldato
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16 Oct 2009
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Essex
Depends on the max ambient really, according to Intel it's 72.7*C.

IMC/VTT on auto is imo dangerous, I would stick to 1.21V max. Rest volts seem fine.

Run IntelBurnTest 2.3/2.4v 20 loops in Custom stress mode, using 2560MB Ram or more.
 
Soldato
Joined
8 Jun 2006
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12,638
Location
Hertfordshire
Guys

Would I be able to get 4ghz out of the hardware mixture below do you think?

i5 750
Corsair H50-1
OCZ 4GB KIT (2 x 2GB) DDR3 1600Mhz PC3 12800 GOLD SERIES DUAL CHANNEL KIT (8-8-8-26)
Gigabyte GA-P55M-UD2 Intel P55 (Socket 1156)

Will I be ok for 4ghz with that combo do we think?
 
Soldato
Joined
16 Oct 2009
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Location
Essex
Probably not. The memory you chose is rated for 1.8V if I'm correct. It won't do 1600MHz within safe voltage limits unless you downclock it. It's also quite expensive from what I've seen.

Gigabyte UD2 should be doing 3.8GHz without problems, I saw couple of posts in this Forums claiming 4GHz overclock as well.

My advice would be get a cheaper air-cooling solution for this combo and a more expensive board unless it has to be mATX.
 
Soldato
Joined
8 Jun 2006
Posts
12,638
Location
Hertfordshire
Probably not. The memory you chose is rated for 1.8V if I'm correct. It won't do 1600MHz within safe voltage limits unless you downclock it. It's also quite expensive from what I've seen.

Gigabyte UD2 should be doing 3.8GHz without problems, I saw couple of posts in this Forums claiming 4GHz overclock as well.

My advice would be get a cheaper air-cooling solution for this combo and a more expensive board unless it has to be mATX.

Yea just read about the ram volts! Didn't realise this when I brought it :(

Board was more base on price than anything! Damn it, will have to make a few changes I think...

Any recommendations on a board?

Many thanks!
 
Last edited:
Soldato
Joined
16 Oct 2009
Posts
8,917
Location
Essex
Well, best bang for buck is definitely UD5 here. You cannot really get anything better for £120. I would get one myself if I was to build 1156 system now. I see you are looking for offers from other retailers thus I'm not sure what to recommend you. It depends on your current and future expectations for a mobo.
 
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