I have roughly 15 A600's and i have tried the ram expansions in most of them. Results have been scattered. Some CPU's run hotter than other, may be put down to brittleness and other wear factors. Most legs were dirty and all required a cleaning of the legs as there was oxides on pretty well all the legs. 2 of the machines when i attached the fastmem board overheated and would last only about 10 minutes before freezing started. I pointed a regular house fan on them and ran superfrog demo (my basic testing) and it would chirp merrily along
All my A600's have been recapped and are what i consider to be in reasonable to good health but chip temps vary from machine to machine. I think age is a factor and just looking at how clean a computer is, is not a reliable indicator of the motherboard itself. It is a bit of a crapshoot with these machines as to how well they behave, with its basic config they will probably chirp along forever but putting extra stress on them could be too much for some of them.