Bitminter doesn't really have a lot of customization.  It is a very good miner made by the pool author for "casual" miners.  If you want max control you should look at cgminer.  Try adjusting core clock and memclock.  I find 800/300 a good place to start.   I run most of my cards at 820/190 some slightly higher, some slightly lower.  Each card is unique in what it can handle.

Once you get a miner stable for say a couple hours they may still go dead after days.  Bring the clock down slightly.  You will find the final clock which is stable 24/7 for weeks (sometimes months).  I have one rig going on 48 days of uptime (I haven't even upgraded cgminer because I want to see how long it can go).  Barring no power outages I think it could run until summer w/ no downtime.