Hello everyone, recently my computer (which has run for ~2years in its current configuration) has been experiencing total system freezesjust recently.

Equipment in question:

Mobo: ASRock z77 Extreme 6

http://www.asrock.com/mb/Intel/Z77%20Extreme6/

*I believe a year or two ago, it was this same board model thatblew a capacitor (which woke me up), and I had that one rma-ed (computer wouldnot boot at all).

Ram (4gb x4): G.SKILL Ripjaws Series DDR3 1600

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231314

CPU: Intel Core i5 2500k

http://ark.intel.com/products/52210/Intel-Core-i5-2500K-Processor-6M-Cache-up-to-3_70-GHz

What I have noticed is that all 4 ram sticks will run bythemselves and together in the B1 and B2 slots, but the boot process will failwith error 55 (memory not installed correctly) when using the A1 or A2 slotseither by themselves or with a second stick in either an A or B slot.

I've also tried clearing CMOS both with the button provided on the board and by removing the battery for a period of time, no change.

I am guessing that points to a Mobo failure? Is thereanything else I should try? Just before taking the computer apart, I ran Memtest for 1 full pass which found 0 errors(not sure what that means given my current findings).

Any ideas are appreciated, thank you for reading.