My power switch

[Raymond27]

what four wires do I need to touch to start pc?

[savvy2]

NO PC told just short 990,  that is not a full # nor posted Product ID#  10x better.

there is no spec for  for this .

but if you held the factor power button assembly in your hand (did you lose it??????)

we can test the path with a meter, (ohms mode)

find what pins the are power.

one is ground and the other is power on true + low logic 0v.

the power pin has pull up resistor holding that pin to 3 or 5vdc.

nothing more needs to be known lacking HP docs that do not exist.

most top made MOBO we can ground each pin with no damage (testing ),  not saying do it, but is huge hint that.

done many I have for this exact thing, for others, that just must know but all OEM PCs this is their secret.

the jack is keyed too so can not be plugged in backwards or offset.

eg; on my HP xw4600 jump pin 6 to 8.

on xw8400 this ,my point it is secret and all model series are not the same, same here, XW

see how they did this calling Tyan for help:> wow , amazing,  sorry no 990 hacks known by me 😅

most pins have protection resistors (not GND) but are like 100 ohms, limiting current below 50mA and safe, as gen. rule.

Pin 13 I'd not mess with, on this PC.

[savvy2]

no story told?

1: someone stole your CASE (PC) or stole the front panel>? (now that is amazing if true) 😂

2: bought this mobo off fleabay only to learn hp does NOT SPEC this out nor does HP sell DIY MOBO !@!!! 🤔😐😲

next time (So sorry) Avoid  OEM used parts. (unless deep hacking is fun, I do so, I am sick) i can do yours if in my hand !!!.

and buy Asus.com or Gigabyte mobo and omg  the free manual covers all this for sure  even from 1995 to now.

sorry I google this and no hits on 590  , seems you are in a small group of hackers., (and well loved)

the funny part (not) hp manual oddly documents all industry standard jacks and slots, then skips OMG all thier custom jacks and ports , what waste of printed paper.  (how totally redundant is that>?)_ rhetorical.

I do hope this is found for you

what I do is reverse engineer the panel first.  it is not hard, but is tedious even for me and lots of practice for 55  years on the job. (retired 10)

[Raymond27]

MY computer is...HP pavilion Desktop 590-POxxx. Device name Desktop-NCC4NV7. Device ID 7678cooE-7964-457997AO-43CB-8361185E

[Raymond27]

On the four peg power switch you touch the yellow and green wire to start pc. PC is not pirate. I bought it at Wal-Mart. I like the green light on cover....