Thanks all for the advice! (Lots of smart folks on this forum, clearly.) I'm no electrical engineer, so instead of trying to follow all the posts in this thread, I just bought a fan and installed it from one of the links to see what would happen. Put in a Vantec Stealth SF6025L (suggested by poppagene) for $9.78 shipped. (WAY less than some companies were trying to charge me.) Fan is so quiet I didn't know if it was working or not. But the results tell me it is. TiVo WAS overheating constantly, unless I set a paper towel with a few Tupperware trays on top of it, with frozen solid water bottles sitting in them (a poor man's heat sink). This would usually hold it for 8 hrs until I swapped out the next batch of frozen water bottles, so at least I could use the TiVo. Now, has been running for over 24 hours with NO overheating, and system info indicates internal temperature is normal.... so, works great! (Still can't hear the fan at all.) Did exactly as suggested (by stevel) re installing the fan (put 3 pin connector over 2 pin on motherboard so the yellow wire not connected), and seems to work fine running off the motherboard without having to get tricky. Thanks again for the great suggestions!