memtest86 with same RAM error despite stick/slot swap

[pdanpdan]

Newbie here, would very appreciate any input you might have.

Running 2010 macbook pro, initially with 2+2GB ram.
Upgraded HDD and installed 4+4GB ram 2-3 years ago without problems

6 months ago began having kernal panics causing forced sleep. Was unusual because I could not wake from sleep no matter what. Had to manually shut down. Was initially once every 2 weeks but began occurring daily.

Initially I thought this was a software issue.
Was lazy and had not upgraded Snow Leopard because was getting close to filling HD.
I upgraded HD, ran disk utility, which didn't show any problems.
Then upgraded to Sierra (my system is compatible) and all updates done.
Ran disk utility again and HDD ok.
But still having daily shutdowns, can occur with any variety of apps, can happen 1 minute after start, or 20 minutes in. I doubt related to temp because can happen right after starting or waking from sleep.

Before I fresh installed macOS and software, wanted to make sure was not a hardware issue.

Ran Apple Hardware Test which found no errors.
Ran memtest in single user mode which found no errors.
Then ran memtest86 which gave me the following:

Errors: 65535+
Error Confidence Value: 18
Lower Error Address: 000ae000000 - 2784.0MB
Higher Error Address: 000affffffc - 2815.9MB
Bits in Error Mask: ffffffff
Bits in Error - Total: 32 Min: 1 Max: 32 Avg: 18
Max Contiguous Errors: 65535+

I re-ran memtest86 with stick 1 alone in slot A, then in slot B. Then again with stick 2 alone in slot A, and in slot B. ALL 5 tests gave the exact same results as above, with the same exact addresses.

Based on this, it is the motherboard? What's my next step? I know my system is old, but I would like to hold off upgrading until the next round of iMacs.

Thanks very much for any advice you could give!

 

[keysofanxiety]

Are you using 1066MHz RAM? Also which manufacturer is the RAM?

 

[pdanpdan]

Are you using 1066MHz RAM? Also which manufacturer is the RAM?

Yes, DDR3-1066 PC-8500, 204 pin as was recommended. OWC brand...

 

[ZapNZs]

Did you try running the test with the old RAM you removed? Further, if you put the old RAM back in, do the problems still persist?

 

[pdanpdan]

Yes, actually all tests were done with the old RAM. After I saw that the exact locations were affected whether Stick 1 or Stick 2 alone in either slot 1 or slot 2, I assumed there was something downstream and did not think that new RAM would help. Testing errors do persist with old RAM.

 

[curmudgeonette]

Lower Error Address: 000ae000000 - 2784.0MB
Higher Error Address: 000affffffc - 2815.9MB

Hmmm, 32MB of contiguous address space, with all bit positions having errors? It feels like this is an I/O address range that memtest86 tried accessing as RAM. In other words, you've found a red herring. Your system problems are likely unrelated.