Peripherals not recognized

[savvy2]

100% true never shoot the messenger

• we cant see your system mess up at all , see it hear it. use it.
• we can not do the tests or watch you do them right or wrong, or know what tools you have., nor spare parts
• In fact my PC here, has 1,200,000,000 transistors just in the CPU alone,  and more, else where, so the tests to find any problem can be get complex lacking tools or spares,  its not a toaster, for sure.
• if you lost power, there, it will need the services of a technician, or a persons with spares.  in all cases.
• In a real shop if power issues seen we use  a voltmeter, but I see the HP service book does not support this level of expertise... at all. its mostly  pull and guess book , limited to that skill set.

[savvy2]

id love to see a photo of your system

real USB keyboard

real USB mouse or wireless mouse and keyboard

on the rear of pc is there 1vga jack or 3.

the screen is dead, but all modern screens never do that, the tell you NO SIG , no screen ever stated. there.

makers name nor model ever stated.

we are blind here (all i know HP case number) zero else.

if you find the LEDs dead on REAL USB wired keyboard dead on all USB jacks turned on,.

that means power is bad. for sure.

we then use a voltmeter to find who is dead.

on desk to the PSU< the the MOBO regs

i a laptop, 19vdc IN and all those mobo regs are checked and we prove no modules shorted causes the regs to shut down

that is all i can do blind,

many persons have a system i can not imagine at all.. things old and new mixed

things in PCI slots not disclosed.

and more, endless list of things Im blind to here.

[mdklassen]

>  all modern screens never do that, [they] tell you NO SIG(nal).

My "modern" monitor shows NO SIGNAL when the VGA cable is not connected to the computer.

It shows the same message when the VGA cable is connected, but the desktop computer's power-plug is NOT connected to AC power.

As soon as the desktop computer's power-plug is connected, that "no signal" message stops, and the screen goes dark.

Still, the symptoms match a "dead" motherboard.