Several Issues with my mac mini (mid 2010). Is it RAM? Is it Disk?

Question

I bought my mac mini in March 2011. It's a mid 2010 model with 2.4Ghz and 2GB RAM.

It came with SL and I immediately installed BootCamp and upgraded it's memory to two 4GB, low latency Corsair.

One day, out of nowhere, I got a kernel panic the OS X partition stopped working. The Windows partition worked fine, though. I tried repairing permissions but it seemed to be beyond repair.

I ran a mem test and got a warning. I figured my RAM was faulty, so I switched back to my old 2GB memory that came with the mac, but I got the same error in the mem test. (Really strange).

I formatted the whole system and reinstalled Snow Leopard, put back the 8GB RAM and ran the mem test again, and it passed 100% this time.

I kept using SL for a few months without any problems (did't bootcamp this time) and then OS X Lion came out. I installed it and started having problems again:

• When I download big .rar or .zip files, after uncompressing them, I sometimes get CRC errors and checksum problems.

• My Shockwave Flash started crashes constantly a lot under Google Chrome.

• Occasionally, my screen becomes "pixelated" in random areas (the image gets distorted as if it was magnified and then pixelated).

• When watching movies in VLC (mkv, avi, etc) the video becomes pixelated sometimes.

• Applications quit unexpectedly sometimes.

Did a clean install of OS X Lion, and the issues improved to a certain degree, but still occurs sometimes. I can't really pinpoint the issue. At first I thought it was Mem, then I thought it was the OS, now I don't really know what could be happening.

Thanks for the help!

Answer 1

My gut reaction to this is failing HDD. Something corrupted due to failing sectors the first time, which created the errors you were seeing. You reinstalled, the drive didn't use the failed sectors on the reinstall because SMART marked them bad. After a while, the failing HDD had more sectors go bad, corrupting drivers and other vital files, creating more random errors and problems. The second resintall improved because it didn't use more of the bad sectors, but the drive may be degraded to such an extent now that reinstalling wont fix it. I say back up your data and replace the drive.

There is a small chance it might be video related, but I think the issues would be more consistent and the reinstalls would not have corrected them for any length of time if that were the case.

Answer 2

While I don't discount the other answer (it very well could be your hard drive) I would suspect your RAM controller or RAM slot. The fact that you are able to reinstall the OS without any catastrophic failures (clicking, failure to boot, unrecognizable disk), along with the fact that data becomes corrupt during memory intensive processes, and the fact that your windows installation was only using a portion of your available RAM makes me suspect the controller or slot.

I suspect that when you boot in to windows, the possible degradation of the RAM controller is only affecting the upper limits of the RAM spectrum and you're only effectively using one RAM DIMMs/slot since windows is in 32-bit, the other 4GB RAM module isn't even being used. In OS X, the OS fully recognizes all of the RAM (using both slots) and this is where you experience failures.

Also, ECC failures are almost always related to RAM failures. And while your RAM may be perfectly fine, your controller could have problems. The fact that you received errors on both RAM tests make this suspicion more plausible.

Try to run OSX using only one RAM DIMM in the primary slot and see if you see errors.