I have run each stick individually in each of the 4 slots available to the Z97 using the uEFI boot loaded Memtest v6.0, which took around 6 hours per stick for a total of 48 hours of continuous testing. I did not enjoy it. I also tested each stick 1 time in slot 1 with Memtest 4.37 for comparison and had no errors after 20 hours of continuous testing for each.

All tests passed with zero errors individually, however the first test I ran with two sticks failed with a single error and the second test failed with 2 errors.

These are rated to run at 2400 MHz so I configured the motherboard to compensate, including 1.65v. I'm currently running the test with the default settings to see if this is the issue. If it is, is this a RAM issue or a mobo issue?

do you get any issues except the memtest, in OS or games?

I get no major errors in games except when I'm using texture mods and I can't prove that isn't related to the program itself. No Blue Screens either. I've changed he profile to XMP 1 per CptSpig and am re-running the Memtest. Maybe it's because I set the Memory configuration manually in the BIOS. Will post results after the 12 hours has elapsed. FWIW, this is brand new RAM from Corsair because the old RAM was showing massive errors that 'were' actual because each stick also failed individually.

just trying to understand what brought you to do memtest at all.
usually it's a way for troubleshooting and clarifying issues.

I'm running an i7 4790k. I ran memtest on the first set of RAM because I was having checksum errors in Steam and would have to constantly download files. I then RMA'd the RAM, installed new RAM, checksums worked so I decided to memtest just to ensure this RAM was good at every address. That lead me to test the sticks individually in each slot and finally test them together.

This build is brand new so there isn't any debris in the memory slots but I can see how that would cause an error immediately on the memtest. Most of mine happened much later, during the 3rd or 4th stage. I do actually use the same UPS brand and my 80+ Platinum rated PSU is rated for twice the watts I'm drawing. Average idle temp for the processor is 30C. It's 'water cooled ' using a Nepton 240XL. I set the memory settings in the BIOS manually and I really think that might have been the problem. I'll know once the test, which is currently running, completes. I think my full spec is in my profile.

Thank you all for your input on this issue. After 2 complete memory tests, one of which was on the default 1600 MHz and the latest using the XMP 1 configuration for the EVGA Z97 FTW, neither had errors and I'm now generally confident that this was a misconfiguration issue.

Thanks, I am glad I could help!

bcavnaugh
I have found the a Bent CPU Pin or Two can also cause this.

Although I do appreciate the input, these chips don't have pins anymore. The motherboard does, in a way, but the chip doesn't sit right if they're bent so it's much more difficult to mess up. Also, you'd have to bend exactly the right pin related to the memory channel and this wouldn't exhibit erratic behavior but rather consistent results for a specific or all memory channels. The system likely would not boot into the OS or would Blue Screen.