Prime 95 fails Large FFTs but is fine with Small

Hello all,

I just recently bought an AMD FX - 8150 and just recently went to run prime95 without any OC just to test the chip at stock speeds and make sure I didn't get a bad one.

I went to run the second option at first (In-place Large FFTs) to which my computer completely froze up immediately (no keyboard or mouse input) resulting in me having to hard reset the computer. After the restart I chose the first option (Small FFTs) and the program ran fine for 5 minutes (3 tests) with no errors and CPU temp never got above 36C. I'm thinking one of my memory sticks may be bad or the current memory I have may not play well with the new processor.

Here are my specs:
AMD FX-8150 stock speeds and stock voltage
Corsair H80 liquid cooling (intend to OC as soon as i get this problem fixed)
Sabertooth 990FX
Asus Radeon HD 7870
GSkill Ripjaw 8GB ( 4 x 2 ) DDR3 1600 ( F3-12800CL9-4GBRL )
Not sure about PSU, i know its XFX though and 80 PLUS certified
OCZ Agility SSD 120GB


I am about to run memtest and I will get back here with some answers, this thread might be for moot if I find any errors on one of my sticks. Thanks in advance though
4 answers Last reply
More about prime fails large ffts fine small
  1. anonymous1 said:
    Memtest is a great idea. I would also check in your BIOS that your RAM settings are correct.

    I loaded optimized defaults in the BIOS so I doubt its the memory settings in the BIOS. Also, memtest just finished and no errors were found, so the memory is ok. The only thing I could possibly think of at this point is a problem with the speed of the FSB. Does anyone know if this could be the case and if so, how would I tweak the speed in the UEFI BIOS as I went into the AI Tweaker but couldn't find an option for FSB.

    I'm slightly new to the OC scene, but I know most of my stuff from classes in college, just no hands on experience.

    Thanks in advance.


    When I get back from class I'm going to try loading the XMP profile in the BIOS and see if that makes any difference. I'll be checking up on this thread in class, so if anybody else has some insight it would be greatly appreciated.
  2. Check your vcore voltage in BIOS.
  3. knightdog56 said:
    Check your vcore voltage in BIOS.

    like i said, everything is at optimized defaults, so everything like that is normal. Although I will check anyway and get back here with some answers as well as load the XMP profile I previously mentioned
  4. Reporting back.

    Changed the memory to the XMP profile and it seems to have fixed the problem at stock settings. I am able to run the Large FFTs without the computer instantly freezing up. I'm going to let prime run for 5 minutes and report back if there are any problems. Thanks for the suggestions everyone.

    Ill be back again after I OC if prime runs ok for now.
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