i5 750 overclocking help

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OpenToSuggestions

Soldato
Joined
5 Aug 2006
Posts
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Location
Derbyshire
Hey all,
I had a nice 4ghz overclock on my i5 750, but as I reinstalled Windows 7 last week I thought I would upgrade the bios on my Gigabyte P55A-UD3R to version F13 (was on F10 before that). I had updated it several times before and had no issues with the overclock.

With the F13 bios and the clean install, I ran IBT on max and it failed after 2 runs. It also had a bsod whilst browsing the internet, so clearly not stable.

The screenshots are of my settings (from the i5 overclocking thread about 6 months ago but they are still the same). I have just run two passes of memtest86 V4.10 and no errors.
I never did manage to get speedstep to come back on for the overclock (although this is probably not connected in any way).
Thanks!
 
Hmmm look similar to my settings. I'm on 900mv for both clock drives but not sure that makes much difference. I'd enable the thermal monitor as a safety feature. Main difference is I need way more QPI/Vtt than that to support the 200 BCLK - I'm on 1.3. My core is also 1.375, but it droops under load so I have LLC on level 2. My PCH is 1.1 and CPU PLL is 1.9. RAM is set to 1.66 but it droops to 1.648 which is about where it should be. What are your memory settings?
 
Liampope said:
Hmmm look similar to my settings. I'm on 900mv for both clock drives but not sure that makes much difference. I'd enable the thermal monitor as a safety feature. Main difference is I need way more QPI/Vtt than that to support the 200 BCLK - I'm on 1.3. My core is also 1.375, but it droops under load so I have LLC on level 2. My PCH is 1.1 and CPU PLL is 1.9. RAM is set to 1.66 but it droops to 1.648 which is about where it should be. What are your memory settings?
Click to expand...

The thermal thing is on, my mistake (those screenies are old).
The ram is running at 8-8-8-24. The rig was fine until I put this latest bios on. I have LLC off and could increase vcore a bit but I read in a previous thread that 1.21v is the absolute max for qpi/vvt on an i5 quad.
 
mglover070588 said:
I read in a previous thread that 1.21v is the absolute max for qpi/vvt on an i5 quad.
Click to expand...

Nah that's old news. It was always 1.4 Vtt for i7 (almost the same architecture) and also 1.4 for the Xeon equivalent of i5, so something funny was going on. Intel then released an updated i5 datasheet and had raised the odd 1.21 limit up to 1.4 in line with the other chips. There was much rejoicing among 1156 i5 overclockers :)

http://forums.overclockers.co.uk/showthread.php?t=18155270
 
Last edited:
Thanks Liampope. Come to think of it, I read that post when it the thread was new, but I only skim-read it as I already had a stable 4ghz overclock.

Have set vvt/qpi to 1.21 and will run IBT to check it is stable.
 
Tried the old bios?

I know some UD7 bioses were quite funny and would really affect the clocking of chips - would have to find the best one for you.

Also, in some of the later ones it changed how much LLC worked, maybe something similar and now its not getting the same amount of power?
 
mglover070588 said:
I always turn LLC off as I never know how much it is compensating.
Click to expand...

You can keep an eye on it in CPUZ when you go on/off load. If I didn't use LLC I'd just have to have my BIOS vcore setting a few notches higher so that when it drooped under load it was still where it needs to be. That would mean slightly higher idle temps.
 
LINK

Intel Processor Power Delivery Design
Guidelines and Specifications: Vdroop Explained


Really worth a read - there is a reason why we have Vdroop.
 
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