I cannot speak for the others that answered, but it is difficult to give proper advice without knowing what your budget is and what you plan to do with your system.
As for the problems you have with your setup:
#1 you could look at putting your money into water cooling your system and the GPUs, that will save you space after installing the water blocks.
#2 I have the same board and bought an internal powered USB hub, it works like a charm.
#3 If you have random BSODs and crashes you might not have your overclock as stable as you think.
P.S. Is there a reason you need your RAM running at 2600?
Now for my suggestions:
If you are really set on upgrading (which I agree with HiV, there doesn't really need to be a reason LOL) you might want to start with which CPU you're going with. If you are looking at Haswell start looking at the Haswell socket boards. If you want to put the money into an Ivy-E then look at the 2011 socket boards or more probably wait for the Rampage IV Black Edition to be released.
I hope this helps some.
I'd rather be a smartass than a dumbass!!!
Maximus V Extreme - 3770K @ 4.5ghz - Kingston Hyper X KHX24C11K4/16X 16GB @ 2400mhz
Corsair Hydro Series H80i - 2 x MSI GTX 770 Lightning - Samsung 830 SSD 256GB - WD Caviar Black 2TB
Xonar Phoebus - Corsair AX1200i - Antec Eleven Hundred - LG 27EA63V