new results! today i want to enter bios, and found, after i entering the bios settings, computer completely lock up. think, PSU is not good, switch to another - liteon PS-5311-tm, 310w
but nothing changes. then i swap trident pci video to s3, and then i can get into bios without problem.
but i see, with that PSU power consumption is smaller - on a login prompt only 0.33A versus old 0.40A!
not bad...

Interesting topic

It's hard to obtain the best performance/Watt with older hardware!

My home server is currently a P3-933 with 2 old IDE drives, and integrated graphics on the motherboard. Approx. ~50W idle, ~70W under load.

For a more powerful server at low cost : Pentium-M cpu's are nice (you can find cheap cpu+industrial motherboard on ebay).

about two months ago i replaced choosed PCI videocard to ATI 4350, for use it for seti@home data crunching. got computer power consumption about 86w on idle ( no work on videocard) and 95 - 98 w ( videocard crunching data). after about month of usage swap it to ASUS GT630 rev 2 ( gk208) PCIe videocard with 1 Gb RAM.
looks like it a bit less energy consumption, and about 4 - 5 times better performance. on new videocard computer consume about 81 - 82w when no tasks for GPU, and about 91 - 93w when crunching data. very good, even apart of that, with nvidia i not need to running X server to use GPU in boinc, and better stability - with ati i get some issues, when screen freeze and cannot awake....