Brian:
Also true, but , two things.
one is, with the above methods you can easily wire a switch and power off the secondary psu on queue, without turning off the computer. Granted that it can also be done with your's (series with wire from the secondary psu), but you only need to void the secondary psu warranty
, not both, as you need to hack , at least, the mobo connector on the primary. Specially when the main one is an expensive one (... and money matters).
second one is that i haven't seen a "mod" like that (doesn't mean it doesnt exist), and , honestly, i wouldn't feel confortable with it. Just don't know how the PSU's or even the motherboard would react to it. They can be picky
.
JSimmons:
The diode is only a safety precaution.
http://www.procooling.com/articles/h...pumps_-_p1.php
example.
About the relays.
Well, you can use which ever suits you better. The only thing it has to be is 12v DC on the command section (coil), which are both.
If you check the specs they state a 70mA on the 12v coil, on each.
The contact section on both can handle the mains at 5 A (at least), and a psu usually absorbs about 2, larger ones 3 but , AFAIK , never over.
If you choose to close the PWR_ON and GND, you'll be dealing with very low currents on the contact section, so, you wont have issues there.
You can use the same relay for both methods.
Either way, which method are you planning to use?
cut the mains or just wire the PRW_ON , or brian's method?
PS : if brian's, then you should get this :
http://www.digiconcepts.com/cables_power_12.htm
Keeps you from hacking in the mobo connector form the psu (voiding warranty).
and, do use a switch for emergency override.