Short version of question: Does anyone have an MSI FM2-A85XA-G65 motherboard, who can confirm that all four memory slots work?
Long version: Several months ago I bought an MSI FM2-A85XA-G65 motherboard at Newegg. At that point I installed an AMD A8-5500 processor and two sticks of Corsair Vengeance 8 GB DDR3-1866 memory, and put it into my file server. I installed the RAM in slots 1 and 3, as directed in the manual, to enable dual-channel memory access.
It seemed to work fine, so I bought a second identical mobo (which arrived dead, but was quickly replaced by Newegg) and set of RAM, installed an A10-5800K, and put that into my production Linux machine. Again, it seemed to work well.
Eventually I happened to notice that on the server only 8 GB of RAM appeared in the BIOS. I tried each of the slots and memory modules individually and in various combinations. I even swapped processors with the production machine. The result was that putting memory in slots 1 and 2 worked (showing a total of 16 GB), but any memory in slots 3 or 4 was not recognized. However, all four memory slots in the production machine worked, and I confirmed this with both processors.
I contacted MSI and arranged to ship the defective mobo back to them for replacement under warranty. I did not want my file server to be down in the interim, and I had another machine I wanted to upgrade, so I bought a third identical mobo to use. That one had the same problem -- only memory slots 1 and 2 worked. I tested it thoroughly with multiple processors and memory sticks.
I sent the defective mobo back to MSI and they sent me a new one. This has the same memory slot problem. So I sent it back. The replacement arrived the other day and shows the same problem. I contacted MSI yet again and they said that nobody else has reported memory slot problems on this board and it must be my processor.
So my score so far is, out of six boards of this model, I have: One where all four slots work. One which was dead on arrival. Four where only memory slots 1 and 2 work.
Before I tear my other machines apart and start swapping processors again I thought I would ask if anyone else has this exact model motherboard and could confirm that all four memory slots either do or do not work. According to MSI you should be able to just plug a single memory module into any of the slots and it will work (and it does on the one mobo I have which works correctly). If you have not yet used all four slots, this is a good time to test them so you know if you can expand your memory in the future.
Thanks in advance to anyone who can help.