i have an old DFI C586VX (REV. B+) (see http://www.embeddedlogic.com/TH99/m/C-D/35241.htm) motherboard that can't boot (cpu fan works, but no keyboard activity, no beeps, nothing) when powered on and 2 black steel bracket-like fixtures (can someone tell me what these are?) would get really really hot.
the board and cpu look physically ok though (no smoke, burnt marks, popped transisters etc). the cpu is an intel p166 classic. clock speed is set to 66Mhz,multiplier to 2.5, and voltage at 2.8 (i've tried 3.3v as well, same result)

is this an appropriate setting?

my machine specs:
serial keyboard
RAM: 64MB (4 x 16mb)
CPU: p166 classic
power supply: 240V
display: AUS 3DExplorer (S3 Virge GX2)
(haven't attached any other devices yet)

Where do these bracket-like fixtures connect to the motherboard?

at the edge. screwed on. look at the image on the link i posted....those brackets are located directly above where JP11, JP9 and JP8 are located. i think they are heat sinks???

They most probably are heatsinks, and unless you have misconfigured the jumpers on board then you board sounds like its dead. Only thing i can suggets doing however is CMOS clear. There is a very slim chance that this will do anything however.

Yep its a heatsink. I'm sure a voltage regulator sits inbetween the fins. If it is getting way to hot to touch then it might be bad or one of the voltage ouputs of the power supply might be toast.