This wasn't the end of the world, so I didn't give this much importance. This weekend I had some extra time to spare, and I've now determined that if I boot with nomodeset, the monitor properly goes into powersave mode.
That seems to be the only difference. Everything works fine either way, except that by default DPMS does not work automatically.
I thought that, perhaps, with the oddball video card on this older server (mach64 chipset) DPMS is not implemented when the video card is in VESA mode, but I can run 'xset dpms force off', and the monitor goes into powersave mode immediately.
Is this a bug, or, despite the fact that DPMS is apparently working, in VESA mode, this may not be supported on my hardware?
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