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TECHNICAL BOARDS => Technical Support => Topic started by: JoeB361 on July 25, 2012, 10:53:36 PM

Title: Errors BEFORE OC - Prime95: Expected less than 0.5
Post by: JoeB361 on July 25, 2012, 10:53:36 PM
A post I made on another board (overclockers forums).
I'd been asking Sin about it, but I can't keep constantly pestering the same guy :P

I recently got a new custom build (put together by a friend).
It is:
i5 2500k - CPU
Gigabyte UD5H - Mobo
MSI GTX 670 - GPU
Corsair Vengeance 2x4GB 1600mhz - RAM
Noctua NHu9b - CPU cooler
CM Storm scout - Case
CM silent pro 700w - PSU

If you need to know anything else, just ask.
I planned on overclocking, and started preparing by downloading all required software.
I ran Prime95, and instantly got: Fatal error: rounding was 0.5, expected less than 0.4
If I run:
Small FFTs - No errors
In-place Large FFTs- no errors
Blend - Fatal error
Within a couple of minute each 'worker' will usually fail from that error, in a random order.

I have changed NO settings, this build is barely a few weeks old.
No changes in the BIOS, but there is a later version out, would it be worth downloading that?
Everything I have read so far indicates it is a problem with the CPU or RAM.
I ran this memory tester: http://hcidesign.com/memtest/
and received 0 errors.

Picture of the screen on prime95 with temps up:
http://img708.imageshack.us/img708/7466/prime95.jpg

Prime95 with CPU-Z up:
(Core voltage jumped around by around 0.1)
http://img543.imageshack.us/img543/6226/prime952.jpg
Would this be safe to carry on and overclock? Or is it even stable if it receives these errors, as I'm not actually sure what they mean.
Any help is much appreciated, according to eBuyer (where I ordered the parts) I only have a few days to return them claiming they were faulty on arrival.
Thanks, Joe.
Title: Re: Errors BEFORE OC - Prime95: Expected less than 0.5
Post by: S!n!StR on July 26, 2012, 07:13:29 AM
Now that I think about it, check your BIOS if you have power saving enabled.

What it does is it downclocks your CPU and lowers your vcore ( CPU core voltage ) when it's not used much to save power, and sometimes it "forgets" to up the voltage to a proper value when you're stressing your CPU.

Try to disable that and also set your vcore manually in BIOS to stock settings. Looking at the picture you linked the vcore is a bit lower than it's supposed to be, it says 1.188, stock should be 1.200. That's probably what's causing those errors.

Manually set the vcore to 1.200 in BIOS and then stress test again with Prime 95, if failures persist, up the voltage a bit more ( in 0.01 increments ) and repeat the process until you get no errors.
Title: Re: Errors BEFORE OC - Prime95: Expected less than 0.5
Post by: JoeB361 on July 27, 2012, 12:14:36 AM
For updates see: http://www.overclockers.com/forums/showthread.php?t=713074