1 of 2 (2x8GB) Memory Modules Not Working

Hello,

I recently built my first computer, I have Corsair Dominator Platinum 16GB 2x8GB 1600Mhz. I have been having no problems with my RAM since I built my computer but recently my computer has been randomly blue screening saying there was a memory error.

I did a Prime95 test with the one that tested the RAM mostly and after 30-40 minutes it said there was a fatal error. I then got memtest and when I tested with it, errors came up instantly after starting the test and came up one after another. I took out the memory module in the third slot and kept the one in the first slot in and it came up with errors instantly again. I then did the opposite, taking the memory module that was in the third slot and put it in the first slot, taking out the one that has always been in the first slot, and currently running memtest for that one, it is ~43% in and hasnt had a single error yet, so I have narrowed it down to the first memory module that was failing.

NOTE: I tested each module with 2000MB in memtest.

I know this is not a motherboard issue since I have tested the modules in the same slot and one works, the other doesnt.

I am thinking I will just take them back to the store to get a new one, but does anyone have an idea of anything else I should do before I should take them back? I will edit with the results of the second module test.

SPECS:

Intel i7-3770k running at stock w/ turbo boost (3.9) CPU
MSI Big Bang Mpower Z77 Motherboard
MSI GTX 680 Lightning GPU
Corsair AX860i PSU