Maximum safe QPI voltage for i7

45704 Views 15 Replies 9 Participants Last post by crellion, Nov 2, 2009

45nm

Discussion Starter · Mar 10, 2009

With my memory runnning at it's rated speed and my QPI voltage running at about 1.36-1.38v is that a safe voltage for it to operate at ?. Apparently someone on OCZ posted that you shouldn't be running at above 1.65v DRAM voltage and 1.35v for QPI.

1 - 16 of 16 Posts

gooddog

· #2 · Mar 10, 2009

there are two different viewpoints here.
The docs from Intel say what the poster at OCZ said.

However, there are also reports that as long as the difference between QPI and DRAM is less than .5v then you are okay (e.g. if QPI=1.35, then dram can be 1.85v or less).

This reportedly was stated by someone at Intel at another site, but it is not an official announcement.

Lyshk0

· #3 · Mar 10, 2009

iirc intel stated that dram should be kept under 1.65

br3nd064

· #4 · Mar 10, 2009

It's safe.

45nm

Discussion Starter · #5 · Mar 10, 2009

I'm not sure. Should I lower my QPI Voltage to 1.35v and have my memory run at it's rated speed and timings or should I continue at 1.375v as I was previously ?.

gooddog

· #6 · Mar 11, 2009

i run QPI at 1.3 and mem at 1.66 without any problems. Memory is at 1600.
(160x25 for 4G).

I haven't tried below 1.3. I thought that less voltage is better.

Since you have 12G memory, you may need more voltage, I am running 6G memory.

45nm

Discussion Starter · #7 · Mar 11, 2009

Quote:

Originally Posted by gooddog

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i run QPI at 1.3 and mem at 1.66 without any problems. Memory is at 1600.
(160x25 for 4G).

I haven't tried below 1.3. I thought that less voltage is better.

Since you have 12G memory, you may need more voltage, I am running 6G memory.

If I set my DRAM timings and speed the BIOS automatically decides to run the QPI Voltage at 1.375. From what I've read on XS a i7 cpu with 1.65v VDIMM and 1.20VTT should last forever (according to Intel). What is you're timings on that Mushkin kit and how long have you been running at that QPI Voltage settings ?.

http://www.xtremesystems.org/forums/...cs#post3324329

http://www.xtremesystems.org/forums/...hysics&page=61

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gooddog

· #8 · Mar 11, 2009

Quote:

Originally Posted by 45nm

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If I set my DRAM timings and speed the BIOS automatically decides to run the QPI Voltage at 1.375. From what I've read on XS a i7 cpu with 1.65v VDIMM and 1.20VTT should last forever (according to Intel). What is you're timings on that Mushkin kit and how long have you been running at that QPI Voltage settings ?.

I had the same issue - auto gave me 1.375 and then I read that the max is 1.35.

The mushkins are at 7,8,7,20

I have been running them a couple of months. I don't run 24x7 but I have done a lot of prime and IBT runs (since I was experimenting with other CPU voltages).

This weekend I will try to lower the QPI to 1.2

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Blameless

· #9 · Mar 11, 2009

I intend to run my setup at 1.424 vcore, 1.395v uncore (qpi/vtt), and 1.74 vdimm until the chip dies, or I upgrade and give this one to my GF (at which point it will be run at more "reasonable" voltages)...which ever comes first.

My money is on this chip lasting quite a while.

http://download.intel.com/design/pro...hts/320834.pdf - page 22.

Yes, the max QPI voltage in the Intel white papers is 1.35v. So what? Plenty of people have been using well inexcess of this for quite a while. You can scarcely get above 3.4-3.6Ghz uncore without it.

Also, the absolute max vddq (vdimm) is stated to be 1.875v, not 1.65v. The 1.65v only applies at stock 1.1 QPI.

45nm

Discussion Starter · #10 · Mar 11, 2009

Quote:

Originally Posted by gooddog

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I had the same issue - auto gave me 1.375 and then I read that the max is 1.35.

The mushkins are at 7,8,7,20

I have been running them a couple of months. I don't run 24x7 but I have done a lot of prime and IBT runs (since I was experimenting with other CPU voltages).

This weekend I will try to lower the QPI to 1.2

That's what I am at for now. I did run my QPI at 1.35v but not for very long and it ran without issues. I'm wondering if it is possible to run my QPI at 1.2v at DDR3-1600 and at 8-8-8-24 as I am not at that the rated speed or timing right now.

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StormX2

· #11 · Apr 8, 2009

you might have to run them at 9-9-9-24 if lower voltage. 6 Channels at once at 1600mhz is pretty taxing.

devhen

· #12 · Oct 1, 2009

Quote:

Originally Posted by StormX2

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you might have to run them at 9-9-9-24 if lower voltage. 6 Channels at once at 1600mhz is pretty taxing.

StormX2,

I agree. To get my d0 920 to do ddr3 1600 6-7-6-18 as per my Mushkin specs I had to give it 1.435 volts on the QPI. This is higher than most have had to use (most people don't need more than 1.375v on the QPI for these settings). Do you think that I am safe running QPI 1.435v and DRAM 1.65v ? Ironically, the 'auto' setting for QPI/Vtt voltage on my EX58-UD3R is 1.435v when the memory multiplier is set to ddr3 1600. But is it safe? I've heard reports that as long as the difference between QPI and DRAM is < 0.5 volts you are ok. What do you think ? If I am risking shortening the lifespan of my i7 I will probably clock the RAM back down to 1066 or 1333 and just tighten the timings to make up for the slower speed.

Thoughts?

Thanks,
Devin

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crellion

· #13 · Nov 1, 2009

Now here's something weird - just finished a new Core i7 920 build and here are my specs:

GA-EX58-UDR3
6GB Kingston HyperX T1 2000MHZ DDR3 Triple-Channel
Core i7 920 - Stock Speeds

If I do a Profile 1 on my XMP (this HyperX supports XMP) - the mobos sets my DIMM Voltage at 1.75V and QPI Voltage at 1.6V when I try to run it at 2000mhz.

Is that a bit dangerous?

I tried to do some manual tweaking where I kept the XMP setting the same, but lower the QPI to 1.335V (still within 0.5 plus/minus of DIMM 1.75V) but the bloody machine wont post - so I had to reset the CMOS.

For now - I'm stuck at regular 1066 speeds but I really want to get this HyperX (which I spent galloons of money on) to run at its 2000mhz spec!

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FSF-Foxhound

· #14 · Nov 1, 2009

the ramguy said Its fine running my VTT @ 1.45

crellion

· #15 · Nov 1, 2009

The reason I did QPI of 1.335v because I wanted to keep it below Intel's recommended 1.35v for QPI and still within the 0.5 saftey zone of VDIMM and QPI voltage differences (1.75V DIMM - 1.335V QPI = 0.415v)...

However I am wondering if I should test the QPI voltage settings a bit more by adding small increments of voltages 1.35v + 0.05v increments until I can get the memory to work solid at 2000mhz solid at VDIMM of 1.75v?

crellion

· #16 · Nov 2, 2009

I guess an even better question is does anyone know the optimal mem/vtt pair diff settings for this particular ram (not the same thing as the 0.5 hardware safe range)... Is it 0.3v?

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