Ed said:
Can I turn on my new motherboard, power supply and case just to see
if "the light comes on"? There is NO processor or ram installed. I just
want to test connections. Will I burn something up without the cpu or
ram? Thanks.
Yes, I've done that. Connect case power switch, to PANEL header.
Connect power supply to motherboard. Flip ATX supply to ON position.
Push the front panel power button. The power supply fan should be
heard to spin (if a fan is present - there are a few fanless
supplies now). Pressing the power button a second time, will
turn it off.
*******
The power button is "two state". It is filtered by a circuit in
the Southbridge or SuperI/O. The time constant is four seconds,
if it has been set that way. So under some circumstances, you
have to press and hold the power switch for a minimum of
four seconds, to get it to switch off.
In other words, don't panic if it takes four seconds to switch
off. Normally, that would only happen if an OS had booted and
set it that way. At a BIOS kind of level, it should switch
off immediately.
Another word of warning, for completeness. Some older power
supplies, have a minimum load rating. It may be stated on
the power supply label. The power supply may not regulate
the voltages properly, unless the minimum load is present.
I don't have any technical info, to suggest what happens
if you're using one of those, and the minimum load isn't
met. Do they overvolt ? Undervolt ? Fail to stay within
+/-5% of nominal ? Not really sure. I've never owned one
of those.
If the ATX power supply label makes no mention of a minimal load,
then you should not have to worry about it. Minimal load supplies
seem to have disappeared from retail, or at least the evidence
they have a need for a minimal load, is no longer included.
(At least one supply, used an internal load to meet its
requirements.) You're not likely to run into a situation like
that, but it's worth considering if you're working on someone
else's hardware. Always check the label on the supply, for
evidence of "strangeness" first.
Paul
