So, my MAME cabinet was having stability problems all day. Either it was locking up, the network kept dropping or bits of it stopped working (like the sound). By a process of elimination I managed to make it consistently crash running Memtest86 after about ten seconds. No errors were printed about the RAM, and it did it with both sticks of RAM in the machine.
The BIOS reported the CPU at a toasty 70c which is kind of high, but then my P4 based server upstairs runs at 60, and seems quite fine with that. All the same I went to Maplin, bought some heat transfer goop and gave the CPU and heatsink a good clean. Not that the CPU needed much cleaning, since there was barely any heat paste on it. There was a large chunk of crusty, dry paste on the back of the heatsink too. Lm-sensors now reports the machine running at 40c while under heavy load.
Don’t buy cheap hole saws and expect them to last for more than one use. Also watch out, MDF is really easy to start smouldering. Make sure all the clumps of burning MDF dust are removed and the holes aren’t smoking either.
Today has been a slow, frustrating day. I “lost” four hours earlier just faffing with the machine trying to make it work. I still don’t know why the PC says the BIOS checksum is incorrect every time the power is removed, the motherboard battery is good so all I can think is the flash in the BIOS chip is starting to fail. It wouldn’t surprise me, I did get this motherboard free inside a junk PC case on Freecycle.