IMNSHO use a proper reset chip and/or brownout detector. Adding resistive loads
to the psu outputs may cause it to fail to start under certain conditions.
Startup current is a critical parameter of PC type PSUs because of the very high
filter capacitances on the boards and in the PSU, and because of the various
SMPSUs on the main board, which are usually not current limited. Adding 0.5A
load on the 12V lead of a substandard PSU that already needs to start up 4
drives on the 12V line (but which are known to the PSU makers to start drawing
current a couple of seconds after the main voltage is up, when the BIOS turns
them on) may make it behave strangely.

If you need 5V to work then specify that voltage (e.g. 5V +/-10%) and implement
a voltage monitor or reset chip that detects this and releases reset only then.
The state of the circuit should be such that nothing unexpected happens when the
voltage is outside this range (either way and no matter in which direction it is
changing and how slowly). Imho this is failry basic common sense for any circuit
or system that must start and stop unsupervised.

Peter P.


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist