Issue With Corsair Vengeance RAM

Long Story:

So I decided to build a gaming computer about 3 months ago. I used the same specs that are in this video---->[ame]

These are the specs of my computer when I first built it

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--Processor: AMD Athlon X4 750K Processor

--Motherboard: MSI FM2-A75MA-E35 Motherboard

--Graphics Card: XFX Radeon HD 7770 GHz Edition Graphics Card

--RAM: 4GB (1x4GB) Corsair Vengeance DDR3 RAM <--------------------PROBLEM??

--Hard Drive: 500GB Western Digital Caviar Blue Hard Drive

--Case: NZXT Source 210 Case

--Power Supply: 430W Corsair CX430 Power Supply

--OS: Windows 7

--Wifi: Asus PCE-N15

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I order all of the parts (some from newegg and some from amazon, all purchased brand new) and built the computer without a problem. Started up the computer and used it for gaming for around a month then I started to have some problems...I kept getting BSOD called "Memory Management" and other BSOD's that deal with problems with the RAM. I also used Windows Memory Diagnostics Tool and that said that there was some HardWare problems. So I thought that the RAM was bad and sent it in for a RMA. The RAM I recieved was different than the first. This new Corsair vengeance RAM that I got was now Black, no longer blue like when I first bought it. I didn't really think anything of it so I put the RAM in and still got the same errors and Windows Memory Diagnostics Tool still said hardware errors. So I contacted my local PC guy and asked him what could be wrong. He said I could be getting these errors because I am only using one single stick of RAM in my computer (1x4GB). He let me borrow a set of RAM that he had at his shop. The RAM has "Micro Center" on its packaging so I am assuming that is who the manufacturer is and has a frequency of 1333. I put this new RAM from him into my computer and everything worked fine! I ran Windows Memory Diagnostics Tool again and it said there were no problems. So I came to the conclusion that I must have to buy another stick of RAM. I bought the EXACT SAME kind of RAM again (Corsair Vengeance (1x4GB) at 1600MHZ). Once I got this newly ordered RAM I put it in my computer, along with the previous stick of Corsair Vengeance that I had. Now I have 2x4GB of RAM so 8GB of RAM. However when I use both sticks of RAM I have very bad stability issues. I tested my computer with Windows Memory Diagnostics Tool and it said that there was some hardware problems still! So I tested each individual RAM stick in both of the RAM slots on my motherboard and found out that the original RAM that I owned (the one that was a RMA from Corsair) resulted in Hardware Problems with Windows Memory Diagnostics Tool. When I tested the New RAM (the RAM that I had just bought) Windows Memory Diagnostics Tool said that there was no hardware problems.

So in short...RAM stick #1 (which is a RMA from Corsair) = BAD/DEFECTIVE

RAM stick #2 (which I just bought brand new from NewEgg) = GOOD/WORKING

So Should I send in the RAM that is saying there are hardware problems (RAM stick #1) in for another RMA?

The other possibility that I have heard from somebody is that if I am going to be using two sticks of RAM I HAVE to buy two sticks of RAM together as a package or they will not work.

As of today I have plans on sending the defective stick in for an RMA. This is very frustrating though because this would be the second time I would have to send it in...

PLEASE HELP ME!! :(

Your local PC guy told you wrong. There is no problem running just one stick of memory. I'm not even sure where he would come up with such a thing. Your PC would run in single channel mode then. You are indeed losing quite a bit of memory performance by doing so, but there isn't anything wrong with running a single stick.

The other possibility that I have heard from somebody is that if I am going to be using two sticks of RAM I HAVE to buy two sticks of RAM together as a package or they will not work.

Your actually facing a few issues. You ordered a second stick, although the exact same part number , could be hugely different than your other stick. Corsair views this as mixing memory and there is no way to guarantee that any two random sticks/kits are going to work together. It's not that that wont work, just in most cases it will cause instability.Some do get lucky and it works no problems. Others may need further BIOS adjustments and some just wont work together.

You can try increasing the memory voltage to 1.6v with your system and see if they are stable then. If not , then it would be best to return the two individual sticks and get a single matched kit.

PS, dont use windows memory diagnostic. It usually is not very accurate. Please use memtest to determine memory health.