i5 Overclockers...what is your 24/7 QPI/VTT voltage?

[brencat]

Hi All. Currently overclocking and testing the new toy in my sig. Wonderful chip by the way... currently running 200 bclk x 18 (3.6ghz) with only 1.025 vcore (base vid is 0.99375), LLC on, +0.025 dynamic VID offset, EIST on, Turbo off. QPI/VTT set to 1.25v, and Ram is at rated speed... DDR3-1600 @ 7-9-7-24, 1.65 vDIMM. My target overclock is 3.8ghz and I am 1 multiplier away...hopefully I'll have the time to finish this up tonight. Load temps are 57c Core 1 and 53c Cores 2-4 so very nice atm.

I was under the impression that the max safe QPI/VTT for Lynnfield was < 1.30v for 24/7 overclocking. Now I see that there is some discussion about whether the absolute max threshold is 1.4v or 1.21v per Intel spec. Can anyone clarify this for me?

Also...how many of you running 185+ Bclk with CAS-7 timings like me are using > 1.21 QPI/VTT ? Please post your numbers!

 

[MadScientist]

It was discussed in this thread. As of July, 2010 Intel changed the max Vtt for the i7-800 and i5-700 processors from 1.21 to 1.40.
http://forums.anandtech.com/showthread.php?t=2107892&highlight=

I'm still running my i5-750 at 1.204 Vtt. I'm stuck at 3.7 Ghz. Raising the multiplier to 21 didn't help. Over 176 BLCK, 3.7 Ghz, it fails LinX, all mem enabled, after 2-3 runs. Raising vcore up to 1.4V, or raising Vtt didn't help. At my current settings, Vtt=1.203, PLL=1.903, PCH=1.100, VDIMM=1.60, I can do 3x - 50 runs LinX with no errors.
My CPU's limit seems to be 3.70 Ghz.

How did you determine that your base VID is 0.99375? Is this bios vcore at stock?

I set my CPU to stock, 2.66 Ghz (20 x 133), disabled C1E, Speedstep, and C-State tech, so when it booted up it would be at stock. Using the latest version, 1.56, of CPUZ, at stock it's reading 1.232 vcore. Is this as close to a VID reading that I'm going to get? If it is my VID it's crappy. Intel's specs state that the i5-750 VID range is 0.6500 - 1.4000.

 

[brencat]

It was discussed in this thread. As of July, 2010 Intel changed the max Vtt for the i7-800 and i5-700 processors from 1.21 to 1.40.
http://forums.anandtech.com/showthread.php?t=2107892&highlight=

How did you determine that your base VID is 0.99375? Is this bios vcore at stock?

On my Gigabyte board, after loading optimized defaults, I changed CPU Core Voltage from "Auto" to "Normal", and set dynamic VID to +0.00. Only have EIST is enabled, C1E and other C-states are disabled. Rebooted, went back into bios and M.I.T. status page was showing 0.99375v. Then went into windows and ran OCCT; checked CPU-Z under load was showing 0.97v so am assuming 0.99375 per bios is my base VID. Perhaps I'm mistaken?

 

[MadScientist]

When I did a search on the other thread for What is the VID for i5-700 processors I found this explanation: http://www.overclock.net/intel-cpus/665362-vid-voltage-identification-explained.html

From that post:
"For most CPUs, your VID can be read using CoreTemp as CPUID. For Core i7’s, there is currently not a program that I know of that directly shows what your VID is. To get an approximation of VID on these CPUs, load the default settings for your Bios, but turn off C1E and C-State and load into windows. The vcore reading at idle in CPU-Z will be roughly the VID of your CPU."

I sort of de-railed your thread, so I won't mention VID again.

Back to the OP's original question.

 

[Kenmitch]

Here is an example of my chip running at 4ghz

I'm running with C1E, SpeedStep, and Turbo(For 21x multiplier) enabled.

4ghz.(191x21) loaded vcore 1.34v (+.16875v) cpu vtt 1.15v and idles at 1.7ghz vcore 1.08v which seems pretty good.

My chip doesn't need alot of cpu vtt....Also I have booted into Win7 with it at 4.597ghz for a screenshot only

 

[brencat]

4ghz.(191x21) loaded vcore 1.34v (+.16875v) cpu vtt 1.15v and idles at 1.7ghz vcore 1.08v which seems pretty good.

My chip doesn't need alot of cpu vtt....Also I have booted into Win7 with it at 4.597ghz for a screenshot only

Thanks -- nice chip you have there. I may try again to lower VTT to 1.23. I had a lockup though with 1.21 VTT @ 185 bclk. 1.25 VTT stabilized everything nicely and system appears smooth at 200 bclk. I'm also running RAM at 1600 (200 x 8) with 7-9-7-24 timings. Passed 16 hrs memtest86+ (36 passes).

3.8ghz was my target overclock and I'm doing my final stress tests now. Passed 3hrs OCCT High Data set last night and I'm doing a Prime95 session right now...will be ~ 14 hrs by time I get home from work assuming no errors. Peak temps are 60-58-57-57 and that's where I prefer to leave it with this smaller but still excellent cooler.