i5 750 stuck at 200 bclk

forteh

forteh

forteh

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Trying to find the best overclock for my i5 750 and running into a stumbling block :(

I can run 20x200bclk all day long with 1.3 vcore, 1.29ish qpi, full load 62℃. I have tested the isolated bclk stable up to 220 with 1.37v and the ram previously ran quite happily at this speed (1760mhz) with my i3.

Now with the i5 as soon as I put it any higher than 200 bclk with the 8x ram it won't post. No matter what voltage I increase the i5 will not overclock the ram like the i3 did, is this common or have I missed something silly?

Beers in advance :D
 
Even with 1.4 qpi :(

edit: I also tried taking out the 2x2gb corsair ram and running with just the 2x4gb cruical 1600mhz and loosening the timings to as slow as possible + running at 1.65v - nothing.

What does cpu clock drive do? I tried turning it up but didn't seem to make any difference.
 
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My old i5 760 and Asus P7P55D-E Pro wasn't stable over 200 bclk either. It would run 21x200 no problem but 20x201 or over and it was unstable.
 
Is it possible to force the 21 multiplier 24/7?
I have turbo + all cstate disabled and whilst I can set the bios to 21x it always reverts back to 20x.
 
Not on yours. The 750 only goes up to 20x. I was just saying about mine running 21x200 no problem but anything over 200 bclk just wouldn't work.
 
are you setting uncore freq to twice what your memory multi is? might help

yopu should be able to push more bclk than 200

maybe try a 19x multi and a higher bclk? some cpu's prefer odd or even multi
 
I don't think I have an option to change the uncore frequency, I think it's set to 16x though which is double the 8x ram multi. The uncore still baffles me and I haven't totally got my head around it :D

I'll try it on 19x200+ but I seem to recall trying that and it still fell over. In theory if I can push it up to the 220bclk that I was running the i3 at then it should get 4.18ghz with 1760 ram. Does the architecture of the imc (45nm vs 32nm) affect the maximum possible overclock of the ram?

Bearing in mind I am using this machine mainly for arma3 and solidworks (both of which work better with fast memory) would I be better running the ram at 1760 with slightly slacker timings (10-11-11-29 I think it ran at) or 1600 at 9-9-9-24 or there abouts?
 
its hard to say,the memory controller on p55/h55 is on the mb unlike in the cpu so its slightly different

you could have a less mature bios than with the i3 though idk

you can test the different results of higher ram/looser timings with maxmem program
 
I'm using the same board as my i3, ga h55m ud2h :)
I pulled the 2x2 corsair sticks and tried 19x220 and it booted fine with the 2x4 crucial sticks but crashed after 20 mins or so of prime; I did have pretty low voltages comparatively so reckon I could get it stable.

Unfortunately as soon as I put the other sticks back in it locks back to the 200 bclk limit, will see how far I can push the crucial ram on its own and see if it offsets the loss of the 4gig ram disk I set up using the extra ram. Is it likely to be the fact the sticks are mismatched that's killing it or just because I have all four slots populated?

Thanks for the help so far, will test it and report back :)
 
Right so I have made some progress with the 2x4 crucial sticks installed :)

Currently at 4.2 (221x19 @ 1.375 vcore, 1.35 qpi, 1.3 pch, 1.9 pll), ram is memtest stable at 1768mhz @ 1.56 vram (11-11-11-28 2T). I tried to push for 225 bclk but it just kept freezing prime95 with not bsod to tell me what's wrong.

Either way it's now pushing 60-70fps constant in arma3 editor where as the old [email protected] was getting around 35 with lower settings - very pleased for a 40 quid upgrade :D
 
have you tried with a 20x multi now? with just the crucial memory?

with all four ram sticks in you might need above 1.4 vtt idk
 
I don't think so, I guess I should just punt vcore up to my 1.4v max and see if it will post?
Assuming temperatures are acceptable with 1.4v would I be safe to go further or does the overvolting cause as much damage as the overheating?
 
I tried it with 20x221 @ 1.44vcore and 1.41qpi and it booted ok but locked up as soon as I started a stress test, no bsod unfortunately. I'm only on air so don't really want to push vcore any further.

Dropped it back to 19x221 and the bloody thing won't stabilise in prime now! Running 1.35vcore and 1.37qpi so still got voltage headroom. It completed a full pass of memtest at these settings though so the ram should be good, I'll have to push the vcore up and hope it gets there; I presume the nominal 1.4v maximum is the full load voltage not what's set in bios?
 
Did further testing yesterday, can't get 220x19 prime stable, it's stable for games but they don't push the cpu anywhere near as hard.
I have run 219x19 with multiple ibt and occt runs without any errors (using 1.35vcore / 1.41qpi) and temperatures peak at 76℃. However it still errors in prime but with much lower temperatures, typically it takes about 10 minutes to fail prime; increasing vcore or qpi up to 1.4v at this stage doesn't seem to help either.

I guess I'm hitting the wall with this cpu, not a major problem as it has dramatically improved performance in arma3 and I want to use it as a 24/7 overclock not just a one of bench :)
 
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prime is poo. just use the system. if it stable for what you do then your fine.
i had a system stable for 8hr(run test as i was at work) then i opened firefox and crash.

I test with LinX, and 3d mark. then i just use the system.
 
P4Clock said:
prime is poo. just use the system. if it stable for what you do then your fine.
i had a system stable for 8hr(run test as i was at work) then i opened firefox and crash.

I test with LinX, and 3d mark. then i just use the system.
Click to expand...

Well there is that I suppose, it was arma3 stable at 221 :D
Whether it's solidworks stable or not I will have to test.

The slight ocd in me will have to be suppressed!
 
I have the same issue, my cpu just hits a brick wall at 3.9ghz - I'm currently running 206x19 purely for the faster memory speeds.

Mine wasn't happy with 200x20 at all.
 
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