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VCore Increase to Run Stable Stock?

post #1 of 5
Thread Starter 
I am currently running a 4930K on a Sabertooth X79. I like to stress test my systems at stock using Prime95 25.11 Blend to make sure I am starting out on a stable platform. With this particular build I noticed I was not stable at stock. After some research and a little tinkering I did find stability (a 5.5 hour run of Blend with 10GB memory and a 3 hour run with 1.5GB memory) after giving the vCore a slight +0.02v bump.

I don't know that I've experienced this before. Is this something that is fairly common or do I have some slightly off hardware?

Also, could someone confirm or deny that this board uses the set Turbo frequency across all cores rather than a range depending on how many cores are loaded?

Thanks!
-Tony
post #2 of 5
If the board is using its own algorithm for Turbo, you're not running the chip at "stock."
If you disable any "xtreme" profiles, etc., do you still see the instability?
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Xeon W3520 GTX 470 SLI 3x2GB OCZ Gold 1600Mhz 2xSamsung Spinpoint F3 RAID0 
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BlueStorm
(13 items)
 
  
CPUGraphicsRAMHard Drive
Xeon W3520 GTX 470 SLI 3x2GB OCZ Gold 1600Mhz 2xSamsung Spinpoint F3 RAID0 
OSPowerCase
Windows 7 x64 750W Corsair TX NZXT Tempest 
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post #3 of 5
Thread Starter 
Quote:
Originally Posted by heraisu View Post

If the board is using its own algorithm for Turbo, you're not running the chip at "stock."
If you disable any "xtreme" profiles, etc., do you still see the instability?

The only thing that deviates from setup defaults is the XMP profile on my rather pedestrian Corsair memory. As far as I can tell that is only affecting the bus speed, timings, and DRAM voltage.

I'm not certain but I seem to remember reading somewhere that boards like this run the set Turbo frequency across all cores whereas the intended 'stock' setup is that the Turbo varies depending on the the number of cores that are loaded. I know my 4700MQ does this. Perhaps I'm confusing the two...
post #4 of 5
Thread Starter 
UPDATE:

Last night I decided to fire up P95 one last time with the intention of letting it run overnight. This time, one of the cores instantly failed with a rounding error. I went into the BIOS and gave the vcore another boost with a total offset of 0.025v. Under load, CPU-Z now shows a vcore of 1.176v. With these settings I was able to run a P95 Blend test for 9 hours without issue. The hottest core reached a maximum temperature of 62*C.

Any ideas of what the culprit is here? Do I have a CPU that just isn't up to snuff or is it more likely the motherboard? Unfortunately I don't have the ability to swap either for testing purposes.
post #5 of 5
Thread Starter 
UPDATE:

I think I have the problem solved. I spend some time searching through the different forums and landed on this over at the Asus RoG board:

Vengeance RAM and the X79 Motherboard
Quote:
Originally Posted by HiVizMan @ RoG 
Vengeance ram and the X79 boards here on the ROG forums have accounted for a good 60% of all support issues in the early stages of the platform. Before folks became a little more aware of the issues. X79 is picky about what ram it likes to have in system.

Sure enough I was running Corsair Vengeance RAM. With this new information in-hand I was thinking that I either had a disagreement between the IMC and memory or a weak CPU/IMC (due to the extra voltage needed to stabilize). Micro Center was willing to help me out by exchanging both the CPU and memory. This time around, I went with some very basic Crucial Sport.

A few words of warning:

The XMP Profile for this Crucial memory sets the VCCSA voltage to 1.3v which is complete and utter overkill for 2 4GB sticks of 1600 9-9-9-24 2T. On the other hand the JEDEC profile set the command rate to 1T which is not stable. I left everything at "Auto" but I did set the DRAM bus speed, voltage, timings, and command rate to the values the kit was rated to run at.

Once I had everything in place I fired up Prime and left to work on other things. Over 14 hours later Prime was still running without issue.

Hopefully this information will save the next guy from my headaches smile.gif
Edited by MNiceGuy - 3/31/14 at 8:35am
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