The HD 3870 with the fan trouble did at least last long enough that I wasn't out of luck unable to use belgian for a while and waiting for the replacement. The replacement is (the name is silly, but the card is great) an MSI Twin FROZR III GTX 570. Ooh, is it fast. Then, at the price, weight, and power requirements, it had better be. The cooling system on this thing is heavy enough that the card seemed to self-seat. Once I had things aligned it just fell into the PCI-E slot, which caught me off guard, "Did that that just happen?". I'm glad I went with the gonzo power supply as this beast needs it. The cooling works. Despite the power requirements (38 Amps at 12 Volts - at least for the full system), it's been keeping in the high 50s to low-mid 60s C. And it's quiet. Not silent, but certainly quiet compared to what I had been hearing.
I saw Firestorm claim 90+ frames per second, for what that's worth - not much as the simulator only sends out a maximum of 45 frames each second. I've turned on some of the fancier settings and been amused by the color shading from various light sources.
Things aren't perfect, alas. They are, however, significantly better. If I had more than one Firestorm session going on belgian before and had more than one visible (not minimized) after a while I would get a hard video lockup. The screen would freeze and nothing would move. I could still ping the system and even ssh into it, so I could look around and do a clean reboot rather than hit the reset switch, but it was annoying. That no longer happens. I can have at least two sessions open, though a third does have a problem it's a milder one. When I minimize that instance, even with the other two minimized already, it is almost certain to crash. This, however, is only Firestorm crashing, not the system or the video. I doubt I can blame the video card for this. I suspect it simply lets me see something that may have been there all along.
I don't know what do do about it as nothing seems out of line. I have 6 cores and that's plenty for all that and gkrellm (system monitor) shows it. I have 16 GB of RAM and I'm not hitting swap. The video card (and system overall as far as I can tell) is runnning if not cool at least not hot). And yes, I really need to dig into the log files to see what is really happening. Then, this isn't really a pressing issue. I can certainly get by and don't really need to run more than two sessions. Come to that, I have entire other computers if I really need to that.
There's more good than bad, certainly. Now that I am rid of AMD/ATI's bletcherously wretched Catalyst setup program (which would segfault whenever I tried to actually do anything with it) on belgian I finally have a dual monitor setup. The nice new monitor has the more graphical programs (Opera, Firestorm) while the old 15 inch 4:3 monitor has most of the more textual programs (Pidgin for IM, X-chat for IRC, terminal, Exaile for music, and gkrellm). This separation works well and seems to make the best use of both monitors.