I've been busy with retro stuff lately. My HP Vectra 66XM was acting funny so I decided to put it back on the pile and setup a different 486 system. I tested several boards. One had bad battery leakage and seemed like it might be dead although I got a beep code on one attempt. I got one with 2 VLB slots labeled "Contaq" to boot, but it was missing some of the SRAM chips and seemed slow. There was a PCI board with fake cache, it came to life and then asked for a password (I saw a list of default BIOS passwords here on Vogons but I didn't try to find the right one). Finally I got to a Genoa X4 VLB board with SiS82471 chipset. It is extremely picky about what RAM it will work with. I looked up the manual online to find the jumper settings but I kept getting beep codes until I finally put the right SIMM in the right slot. Later, I managed to find one other SIMM that would work (out of 12) and get it up to 24MB of RAM.
I put it in a Trinity Works 5x86 chip (running at 33x3 for now, with WB enabled), Trident 9440 1MB VLB, Promise EIDE2300+, SB16 CT-1740, NE2000 compatible ISA NIC, and a Quantum Fireball 2.5GB. It all fits nice and snug in a mini tower AT case. The BIOS is Award dated Nov '94, it detects the HDD and mistakenly displays the size as 430MB but seems to run fine otherwise. Appears to have some Y2K problems though.
I also tried out an Athlon XP-M in a Biostar M7VIP-pro board. The CPU is supposed to run at 133*12.5 (1.66GHz). For some reason it boots up at 133*6, but I guess this is actually a good thing because then I can crank up the bus speed and set the multiplier with a utility after booting. I already verified that it works at 166*10 and even 166*11. I don't really know where the voltage is running yet, since I've only booted DOS so far and have no way to check (the register contains 0x0B but I'm not sure what that translates to on an Athlon XP-M).
I tested power consumption on my 286. I wasn't sure what to expect, it has 5 ISA cards, 1 HDD, and 1 FDD. It only pulls 36W from the wall, which is slightly less than my "low power" Win2K box (an Athlon X2 4850e and Radeon 4550) at idle. Later I tested my 486 build and it came in even lower! Only about 32W.