Question PC wont start after using another power supply ?

[never buy asus ever]

I will try to describe in details everything ive done so maybe someone knows exactly what ive done wrong.

I have old dc7900 HP oem pc, also i got radeon r9 280x graphic card not related to this pc, but i bricked it when i was trying to change bios earlier, so since i needed integrated gpu to try to unbrick it, and this pc has integrated gpu i wanted to pull out motherboard, stuck r9 into it and unbrick it, but since original psu from this pc doesnt have neither power or pins for r9 i used my regular psu 500w with needed 6 and 8 pins.

First i just tried if my 500w psu will work on that pc without any r9, it worked normally everything was spinning just regularly, then i got out mobo with all components on it because r9 is huge and couldnt fit in tiny pc case, then i put r9 into slot, turned on 500w psu, im not sure but i think psu fan just worked for a moment and instantly stopped, r9 didnt react, on motherboard little green led was on. So i tried couple more times and since it didnt show anything i went to put it back as it was before.

When i put mobo in case and connected everything as originally, it didn't wanna start, blinking 4 times red lamp and making sound. I researched and in manual for dc7900 it says it may be power supply faulty or cpu.

Now i tried every step to see if mobo or original dc7900 psu is dead, psu is totally fine, mobo seems ok too, so the thing is when i put in 4 pin cpu cable it just wont start anything, instantly blinking 4 times red and beeping, when i pull it out and press power button, psu, fans, everything connected to motherboard seems like starting for about 1,5 seconds and then it all stops and starts beeping again, this time i guess because no cpu power is connected.

So is it possible my cpu died? Or maybe my 500w psu burned out cpu or cpu 6pin connector somehow? Is there a way to be sure whats the problem here, can i test it somehow more to rule out possibilities?

 

[Ralston18]

This:

"so the thing is when i put in 4 pin cpu cable it just wont start anything, "

Update your post to include full system hardware spec and OS information.

Include information about your "regular psu" : make, model, wattage (500w noted), age, and condition.

What beeping do you hear? What pattern of beeps: long, short, and number. For example one long beep followed by two short beeps. Listen carefully.

Do you have the motherboard's User Guide/Manual? If not go to the applicable manufacturer's website and download the manual. Post the link.

 

[never buy asus ever]

This:

"so the thing is when i put in 4 pin cpu cable it just wont start anything, "

Update your post to include full system hardware spec and OS information.

Include information about your "regular psu" : make, model, wattage (500w noted), age, and condition.

What beeping do you hear? What pattern of beeps: long, short, and number. For example one long beep followed by two short beeps. Listen carefully.

Do you have the motherboard's User Guide/Manual? If not go to the applicable manufacturer's website and download the manual. Post the link.

My "regular psu" model is Raidmax RX 500 XT, i know its not the best but at the time of buying didnt have better options for budget, i bought it brand new about year ago, it works very well in general, no problems, i use it on my everydays pc ryzen 3 1200, b450, gtx 1060, 16gb ram configuration.


http://www.hp.com/ctg/Manual/c01549447.pdf - this is manual for that pc which died

4 beepsBlinks red 4 times @ 1 HzPower failure (power supply is overloaded). Check storage devices, expansion cards and/or system board (CPU power connector P3) - this is what it says in manual about problem im experiencing