Edit: Last night, I left the GPU running, but downclocked it to 405Mhz (lowest Precision 2.04 slider will go). Temps on GPU were 65-66C, rather than 70-73C. CPU temps were 81-83C, rather than 86C.
I'm concerned about your cpu temps. (That's 177.8-181.4F!! (That last sentence is more of a note to myself, for reference. I realize that everybody on our forum knows how to convert temperature.))
I'm reasonably certain that you know more than I do, so I won't say anything about thermal insulating material or heat sink fins clogged with dust.
My cpu temps range from 50-78C during this current Primegrid race. The 50C machine is powered by a AMD Athlon 64 FX60 dual core cpu. There is an nVidia GeForce 9800 GT which has been running Primegrid Collen-Woodall gpu tasks for several months. I'm running Debian 64 linux on that machine, and the subroutine which displays the temperature actually displays the temps for core 1 and core 2, and there has been some discussion regarding the placement of the associated sensors, and many think that the reported temps for the cores are inaccurate for that cpu.
I have another machine, and except for the video card and associated tasks it is identical to the first, but the OS is Microsoft Win XP Pro sp3 (32 bit). I am not running any gpu tasks on that machine. Everest reports that the cpu temperature is 63C.
I have a machine powered by an Intel Pentium D 820+ and there is an nVidia GeForce 8800 GT video card (that is not very powerful, but it gives me an extra couple thousand Primegrid Collen-Woodall gpu task points per day.) The OS is Win XP Pro sp3 (32 bit). Everest reports the cpu temp to be 78C, and it always runs above 75C, no matter what project the cpu is dedicated to. When "Smoke" first sent it to me 4 or 5 years ago, I thought that it would burn itself up for sure. However, not only does it keep going (slow and steady wins the race), but it also gives me much less trouble than my other machines.
Rudy Toody provided me with all the essential components necessary to build a machine based on An AMD Phenom II X4 940 Black edition. None of the other computers are overclocked, but the Phenom is OC'd 10%. There are no gpu tasks associated with this machine. Speedfan 4.40 reports the cpu temp to be 70C. This is the first time that it has run so hot; it normally runs ~63C.
EDIT: next paragraph --
So Larry, do your cpu's normally run so hot? How many computers dedicated to crunching do you have; and what sorts of cpu's do you have? How are the temperatures reported, and have you ever had any instability or other problems due to such high temps? Since I originally wrote this, I looked at your signature. I am able to see what computers and cpu's you have.
(I'm not very curious, but I want to know anyway.) Thanks --
Rex