Memory errors: fault or incompatibility?

According to the Corsair compatibility list my MSI P35 Neo2 should work fine with my TWIN2X4096-6400C5. However, I've been having problems which I think I've narrowed down to the memory (which is a replacement I bought a few months ago). The issues are:

• BSODs in Windows (maybe once or twice a day) of varying natures
  
• Occasional non booting (usually after a BSOD) unless left off for a while
  
• Memtest86+ hasn't reported any faults, but the actual computer can hang during running
  

Because the faults are random, it's time consuming pinpointing the problem and I know I need to run one stick at a time to see if just one of them is causing the issue (I'm currently trying different memory to double check my memory diagnosis). But I'm wondering if anyone can suggest whether the memory is likely to be faulty or whether I should try relaxing the timings a bit (I'm using the SPD timings at the moment), even though the SPD 5-5-5-18 should be okay? If so, what should I change?

I should point out that I updated my BIOS - there was apparently a known issue with 4GB memory, but it was addressed in the version I now have.

Thanks for your response, Ram Guy.

By "setup defaults", you mean reset the CMOS settings to factory defaults, I assume? I'll do that and try increasing the voltage as you suggest.

Just wanted to say "Thanks!", Ram Guy.

I've been running my machine for about a week now with the memory at 1.9V instead of the rated 1.8V and so far, it seems to have fixed the problem.

I have mixed feelings about having to do this for memory supposedly rated at 1.8V (and my previous 2GB Corsair memory ran fine on this MB at the lower voltage), mainly from a heating point of view (back of an envelope calcs suggest an 11% rise in power use). However, it seems like the best solution. I may try dropping it to 1.85V and see how it goes on that.

For reference (for anyone with similar problems on an MSI Neo2 motherboard), the memory voltage selector in the BIOS is greyed and the help text / manual suggest this is a read-only value. It's not: you can change it with the "+" and "-" keys on the keypad.

Okay... this hasn't worked.

I've done some more experimentation and determined that it is a fault and it lies within one of the two modules. I've requested an RMA from the place I bought it, but:

• They want to charge me postage both ways as it's more than 14 days since I bought it
  
• They are threatening me with an additional £10 charge if they can't find a fault. As the computer sometimes runs for a week or more between incidents, I'm not confident they'll find the problem

As the product was faulty when I bought it, I don't really think this is fair. If I return the memory back to Corsair directly, what are their policies on postage costs? I'm in the UK, so information relevant to the UK market (if any different from elsewhere) is most appropriate for me. I've looked, but can't find any info on this on their website.