Well, my WRT54GS V.4 has heatsinks and it's in front of an air conditioning vent, but it can still overheat and cause minor network problems. The radio chip doesn't over heat as much when its' power is increased to any number, but when it comes to overclocking the cpu it was pretty much a problem. At 216MHz it works fine. At 228 a bit better with some heat being generated. At 240 it begins to generate too much heat overtime (you can observe this by feeling the bottom left side of the router case where the cpu is most likely to be). At 260 and above you would need thicker heatsinks and more ventillation as the heat can cause problems during data transmission and sometimes the router may malfunction a bit near 300MHz. I observed this when I was playing some online games and my tv screen would show some streaks every once in a while when the router is overclocked at about 280 MHz. Not only that I would also lag out a bit and not be able to login into servers, because of errors (it would say as a message when it wont let me login). But at 216-250 it wouldn't happen as often or sometimes never.