Ambient temp is about 36-39C so its normal for me (window is about 1.5M above the rig), and yes the cards are not using risers. I can lower temps a little bit if I use 150 mem but the 5970 (using a riser and above the 5850s) is not okay with anything lower than 300 mem. Underclocking/undervolting are all done via CGMiner (except the 6870). Using a desk fan to blow air over the rig will only decrease the efficiency. My cards are more than 2 yrs old now, used them for BOINC before I got into Bitcoin. Coolers, fans, TIMs and pads haven't been replaced yet.

Just wondering, does "E" on the cgminer screen stats stand for efficiency or something else? A day of mining results in E:360% but if I increase the core clocks, E drops down to 200%+ and drops even more to about 140% if I go above the default core clock. Using a kill-a-watt, the settings with E:360% gives me a better MH/w.

Specs:
Athlon II 170u (CnQ enabled, 0.9v, 0.7v @ idle)
Gigabyte 890GPA-UD3H
2Gb RAM
16Gb DOM
1x 5970 (625/300 @ 0.95v)
2x 5850 (780/300 @ 0.85v)
1x 6870 (775/300 @ 1.10v)
800w Corsair GS
Windows XP 64, 11.12/2.5, CGMiner 2.4.4

4 x6500 running MPBM is also attached to the rig.