need help with Prime errors

[leebeloola]

I'm trying to figure out which hardware is responsible for the Prime errors I'm getting. I've gone back to default settings and I'm still getting the same errors. I was going upgrade the RAM and get an SSD, but now I'm wondering if I need to replace the CPU and motherboard.

It passes the small FTT test, but I am getting “rounding was 0.5, expected less than 0.4” hardware errors within a few minutes of running the large FFT or Blend tests. I've run Memtest86+ several times overnight for 13 passes and I didn't get any errors. I've run tests on the HDDs and used intel diagnostic tool for the CPU, but haven't found anything. I've also been checking the CPU temp while testing and it's well below 40*C.

System specs:
MB: Gigabyte GA-H55M-UD2H Intel H55 (Socket 1156)
CPU: Intel Core i3 530 @ 2.93GHz (bought it @4.2MHz, but lost settings after bios flash)
RAM: Corsair DDR3 PC3-12800C9 1600MHz Dual Channel Kit (2x2GB) CMX4GX3M2A1600C9
Graphics: AMD Radeon HD 5770 CuCore 1024MB GDDR5
PSU: Corsair GS 600W Power supply (CMPSU-600GUK)
Cooler: Akasa AK-CCX-4002HP Venom CPU Cooler

 

[leebeloola]

Sorry for the long silence, I had to put the project on hold for a while. I ran the small FTT test again and it ran for 17h (I couldn't remember how long it ran for last time).

I tried increasing the vCore to 1.21875V has resulted in the Blend test running for 1h 1m instead of the previous 3m. The max temperature is only 1 degree higher. I increased the vCore again and the test ran for 1h 13m with +1 degree, the next bumb up in V resulted in 1h 20m and again +1 degree higher. Seeing as the time difference isn't that big I gave up on this.

As for RAM, I've tried the following:
comand rate 1T to 2T = errors after 3m
tRC 34 to 41 = 22m
enabled XMP profile = 2m
I did load optimised default when I made changes to a different setting.

 

[leebeloola]

I really don't think it's the RAM. I replaced it & tested it repeatedly 2 years ago after adding it to my pre-existing RAM didn't work. It was the same product number but each set had a different density. I thought one of the sticks was bad, so I tested them all. I had to update the BIOS but unfortunately all the update description said was "improved memory compatibility".

I'd like to figure out if a RAM/MOBO compatibility problem or an old overclocked CPU is more likely. I would really like to understand how to diagnose this problem further. I haven't found anything on testing the MOBO and I'm not sure how to interpret the Blend test errors versus the passed small FTT & memtest.