What to do...wavy shimmeriness when case gets warm

[Cerb]

PowerColor 9800SE, running stock.
When my case temperature hits 38C, I start seeing wavy lines, much like on a bad TV signal (but going up instead of the usual TV diagonal or across), moving up the monitor.
So, what should I do? The card is brand new, eveyrthing in perfect condition. I do not have a better case around--the best I can do is run it with the side off. 39C is the highest the case temp has gotten, but Prim95 gets it there in a matter of minutes, so I surely wouldn't want to do any stressful gaming.

Any auggestions, aside from leaving the case open?

 

[high]

What kind of cases fans are you using and how is the air flow in there? Obviously if it's hitting 39C System temp with the door open, check to make sure the board is properly grounded to the case with all the brass standoffs and what not.

 

[Cerb]

Update: on single-color areas (the background of www.google.com, actually ) I can notice it at 36C.
It's not hitting that temp w/ the door open, just the front panel off (and the side is crewed on, still--not to mention it is much quieter all buttoned up, and should work fine that hot!). The case temp in BIOS on a cold boot is 33C. It's an Enlight 7237 with a single 80mm 28CFM fan on the back and a PSU fan that isn't doing much (Fortron 300w PSU).
However, these temperatures are not higher than my previous case, nor will they likely go down much. I like quiet.
The standoffs are steel, I believe. All the screws are tight on the mobo.

...and yes, I have the additional power connector hooked up on the mobo and video card.

 

[Cerb]

OK, I'm not in the greatest mood right now. Just had SS2 sit there (with god mode on, getting attacked) for the last 20 minutes or so, and w the case temp at only 34C...it did it. The GPU must be getting HOT...and the case airflow is fine. Just popped the side off and the HD is nice and cool (mounted just below the video card in a custom-made cradle), and actually getting warmer with the side off.
I hate it, but it looks like RMA time. :disgust: