...You seem in a trap of sorts to most of us that are serious about performance as relates to cpu speed. Up to a point, the more the better. Within reason, the more the better as for cpu speed. But there is a truth here and that is you do not need any others stamp of yay or nay to do whatever it is that you 'have' to do. And as is what is said most of the time...it is the money thing. Well we or most of us or I know I do now have a money thing. It seems it is the nature of the beast to have a money thing.
You did not hear of or see me post up when about 3 weeks ago I was wrestling with needed a new AM3+ mobo. I needed to replace a borrowed CHV-Z board. I played the game in my head of SaberKitty vs CHV-Z and all the reasons why it seemed a lot silly to get a CHV-Z board and not the SaberKitty for less money. I wrestled it down in the same manner I did when I bought my original CHVnon-Z mobo. I liked the reddish accents of the CHV. Hehehe. What a freeken hoot. I will say that I have NEVER regretted the extra I paid for the Original CHV and now that finally the newer CHV-Z is sitting here in front of me...NO regrets either. I know that within the limits of electrical fallability, this CHV-Z will do what it is expected to do. Be adjustable and run with daily settings and run with cold water pushed by big pumps thru a big arse water block and with no fear of failure of VRMs if I overclock it. That was and still "is" me.
Your trap is in posting about "what to do" but not actually able to do what is suggested. Now that is a trap. You cannot buy used because you fear lack of warranty. You cannot bite the bullet and go ahead and buy a Sabertooth 990FX R2.0. Once it was determined that an RMA had to go forward, you should have just said to self and all others >> I am going to run the MSI board until it blows since I am not going to overclock it or at least not beyond an imposed limit of 4.2Ghz or very close there-to and been done with it.
Understanding where you are is just life. Few are they that can help you out of traps like you seem in. What others may think is totally and completely not relevant to 'your' situation since you are not able to move out of said situation. Therefore I concur completely with mR. sCOTT in that you get the MSI back from RMA and run it until it blows and case close and job done. Based on your preferences, that is what was going to happen in the first place. Nothing to discuss.
Save yourself some wear and tear and mental gymnastics, by getting what you can afford and want and using it. Because we are not going to change our minds about a better course of action and you are not able to take those suggested courses of action. An impasse (a predicament affording no obvious escape) is where you are and the less conflicting conversations about what you cannot do; the better your feelings about your course of action should be.
There are some things just better not discussed in a forum. One is 'what should I do'? Most especially when you know beforehand what you are going to be able to do. If one asks what 'seems' better: X or Y? Well that is going to get a myriad of responses and one can then just tally the pluses and minuses without reflection on one's own situation.
So again I suggest simply to get "your" parts and run them. Discussion is fruitless. Have a good time. Do some fulfilling computering. Job Done.
RGone...