Just run two instances of SP2004 just to make sure it's stable and to make sure your load temps aren't too high.
When you say stock cooling do you have the heatpipe cooler or just the normal cooler? If you have the heatpipe one you should be able to push it a little farther..
I just noticed something though, you should have your LDT ratio(HTT link) at 3 probably. Not 2 like you have it.