BSOD and crashes playing BF3, happens with 2 different GPUs

Well, the remaining DIMM showed 0 errors after 12 passes, so I guess I removed the correct one

What I'll do now is gradually re-install whatever I uninstalled as noted in my above posts and test the heck out of this computer this week-end (read: finally play BF3 after weeks )

I guess I'm going to have to ask a refund on that RAM and buy another set of DIMMs, hopefully I'll have it fast.

In the end, if all goes well and I have 0 crashes, I'll come back and mark this thread as solved.

In any case, your support has been incredibly fast, friendly and focused, so thank you very much!

EDIT: Well, the store at which I bought the RAM told me to do one more test before returning it: As I have an i5 2500K processor they would like me to test by changing the BIOS as follow:

RAM frequency to 1333MHz
Timings to 9-9-9-24
Voltage to 1.25V
Command rate to 2N or 2T

What do you guys think of that approach?

Okay, I finally found some time to re-test both RAM sticks as requested by the vendor.

I attached the two BIOS screens to display the RAM settings I used, as well as the MemTest results: 0 errors after 14 passes.

I'll keep an eye on this as I haven't had a chance to give it a "real" test, but after one long and crash-free gaming session I think i'll be able to mark this one as solved anyway :)

Okay, finally got the new identical RAM kit delivered, and had time to run some tests, I think the conclusion is indeed a faulty RAM kit:

First I ran a positive control test where I reset the BIOS settings to Auto for all items I had changed in a previous post, and re-installed the faulty RAM in the A2-B2 slots
--> Crashes as frequent as before, as expected

Then I placed the faulty RAM in the A1-B1 to see if it could be a faulty slot (mobo) issue instead
--> Crashes as frequent as before, consistent with the faulty RAM theory, but does not rule out the faulty mobo

Third step was to remove the faulty RAM and install the new RAM kit in slots A1-B1
--> Not a single crash in a total of 10 hours of gaming, where I used to have crashes every few minutes. Still consistent with the faulty RAM theory, but does not rule out the faulty mobo

Last step was to move the new RAM to the A2-B2 slots to test them:
--> Not a single crash in over 18 hours of gaming/intensive use.

So in conclusion I think it is safe to assume the mobo is fine and the old RAM kit is faulty, so I'll send it out for replacement.

Here are my lessons learned on this one:

- Even though everyone hopes for a quick fix, ALWAYS perform test steps one by one (e.g. remove ONE supposedly faulty component and test right away). If you change multiple things and the issue is resolved, you won't know for sure what actually solved the issue.

- MemTest results are definitely not 100% accurate unless you leave it to run long enough. I think it's pretty safe to say that running it for less than 10 passes is worthless.
Note that even with enough successful passes (20+ have been advised) it does not replace real-life situations a.k.a. whatever you usually do on your computer that makes it crash.

- If the component you're suspecting is plugged in the motherboard, don't rule out the possibility that the motherboard itself is faulty, ideally have a negative control test with another similar component that is known to work fine

- RAM issues are a pain to diagnose as you can easily have false negatives as I have had. Also there's nothing you can do with your computer without RAM

I'll mark this one as resolved, hopefully it can help other people.

Anyway, thanks a ton for your super fast follow up and very knowledgeable answers.

TL;DR: The RAM was borked in the end, tadaaa