Monarch seems to have alot of problems with their new builds. Have you been th their forums? They have a section for custom systems they have built. i would make a post there and see what they say.
I personally wouldn't make any changes without contacting them first. I tried that myself on my combo and went thru hell to get an RMA.
As for the temps, I guarentee they will tell you they are normal. I had a 3000+ hitting 60C when gaming for <15 minutes, and they told me that was normal. That was when I decided to reseat my HSF and use AS, and the rest is a very, very long story. It all worked out in the end, but I won't buy anything form pre-built from Monarch again.
IMO those temps are higher than they should be, but they are definitely within spec, and are not the cause of your problems. My guess would be the memory. Running memtest will let you know if that is the problem or not.