GA-X58A-UD3R rev. 1 - Errors running Prime95 or LinX tests

[darinf]

I am building a new PC:
Motherboard: GA-X58A-UD3R (rev. 1.0)
BIOS-Version: F5
Graphic:  Zotac GeForce GTX 470 1280MB DDR5
CPU: Intel Core i7 930 @2800MHz (default)
OS: Win 7 64-bit
RAM: OCZ3G1333LV4G, 3 sticks of 4GB
PSU: Corsair HX850W 850W
SSD: OCZ Vertex 2 60GB

I am not overclocking, but I did have to manually set the RAM to 1333 and the timings to 9-9-9-20-1T according to the manufacturer.

The rest of the settings in the bios are default.

If I have all three RAM sticks in slots 1,3, 5, I can run Memtest86 overnight without errors.

However, when I boot windows 7 64bit and run Prime95, I get an error almost right away: "FATAL ERROR: Rounding was 0.5, expected less than 0.4" on multiple threads.

I have tried tweaking the RAM voltages and timings, but I always get this error.

Or I can only get LinX test to run for 5 to 10 minutes before getting an error.

If I install one RAM stick at a time in slot 1, I can run either Prime95 or LinX without any problems. I get no errors with any of the 3 sticks installed by themselves in slot-1.

So, I am pretty sure it's not the RAM or the timings since everything works with one stick.

Do I have a defective motherboard? Can you think of any other reason why I would be getting errors?

Thanks in advance for your help.

-Darin

[Dark Mantis]

With your specs being all high quality makes this a more difficult problem. There is nothing that stands out as being a weak link. I have checked the QVL for your memory and they are not on it. Now I know that doesn't mean that they won't work but it does indicate there could be a problem with compatibility. So I checked to see what OCZ recommends and it is not on their list either. I would say that is your problem, memory incompatibility.

[buzzard]

I am apt to believe that your memory is ok if you are passing memtest overnight.  My experience with the rounding error is that it is a cpu thing.  When overclocking, I get the rounding error when I do not have enough cpu voltage.

What voltage is your cpu set at in the bios?  If it is on Auto or Normal, try manually setting it to 1.35V (I believe this is about the max vid Intel says any i7 930 will have).  Test again with the cpu voltage at 1.35.  If there are no errors, drop the voltage a few steps at a time and re-test until the error comes back.