Pc will not turn on at all with 8pin Molex CPU Cable connected.

[ottovonsanders]

So at first I thought it was the power supply but it turns out that’s not the case. So essentially the only way for the PC to receive power is if I remove the eight pin CPU connector and just plug in with the 24 pin connector it works but, as soon as I plug in the 8 pin there’s no sign of power to the computer it just won’t turn on or do anything.

 

[clutchc]

Are you sure you're using the CPU 8-pin and not the 6+2 pin PCI cable? They are keyed differently and not easily inserted in the wrong header, but it can be done. They are also reverse polarity.

If that is not the problem, do you have access to a voltmeter?

 

[ottovonsanders]

Yes I’m using the cable next to the 24 pin cable that comes out of the psu the e16 and other ones are marked on my psu as red and black. Everything was fine 1 day and the next day I come to turn on my pc Nothing Stupidly enough I threw away my old Psu Thinking it was broken purchased a new one and the new one didn’t work so I essentially Tossed A working PSU. I’m not sure what could have happened I don’t overclock didn’t really do anything new So it’s either the CPU or the motherboard tomorrow I should be able to find out if it is the CPU or the motherboard by replacing with a brand new CPU which doesn’t really make sense how can a cpu die so maybe there’s a problem with the fasteners I’m not sure. At this point since the PC powers on with only 24 motherboard pin connector connected. I think that means the motherboard is fine. I can see all the fans the LED’s and everything pretty much functioning but as soon as the CPU Socket is connected to PC won’t turn on totally dead nothing. Yes I do have a volt meter but I have no experience in using it on computer components.

 

[drivinfast247]

The PC powers and boots into Windows without the 8-pin plug?

 

[clutchc]

Yes I’m using the cable next to the 24 pin cable that comes out of the psu the e16 and other ones are marked on my psu as red and black. Everything was fine 1 day and the next day I come to turn on my pc Nothing Stupidly enough I threw away my old Psu Thinking it was broken purchased a new one and the new one didn’t work so I essentially Tossed A working PSU. I’m not sure what could have happened I don’t overclock didn’t really do anything new So it’s either the CPU or the motherboard tomorrow I should be able to find out if it is the CPU or the motherboard by replacing with a brand new CPU which doesn’t really make sense how can a cpu die so maybe there’s a problem with the fasteners I’m not sure. At this point since the PC powers on with only 24 motherboard pin connector connected. I think that means the motherboard is fine. I can see all the fans the LED’s and everything pretty much functioning but as soon as the CPU Socket is connected to PC won’t turn on totally dead nothing. Yes I do have a volt meter but I have no experience in using it on computer components.

Maybe you better list the system specs so we know what we are dealing with...

 

[ottovonsanders]

No it dose not boot into windows. What kind of understanding is that? It only turns on the psu fan and anything that’s connected to the mobo as well as the cpu fan but, no post because of no power to the cpu

 

[ottovonsanders]

Just replaced Cpu And the same thing happens I’m not really sure what’s going on and if the board was the Issue then why is 24 pin plug powering on everything on the board I’m not really sure what’s going on I have replaced CPU but I kept the same stock fan maybe I should switch it with a new fan to see if that works. I wonder if the second power supply I have is faulty somehow I wish there was a way to test out this mobo but I don’t have another 300 series motherboard lying around so not really sure what to do here

 

[clutchc]

Just replaced Cpu And the same thing happens I’m not really sure what’s going on and if the board was the Issue then why is 24 pin plug powering on everything on the board I’m not really sure what’s going on I have replaced CPU but I kept the same stock fan maybe I should switch it with a new fan to see if that works. I wonder if the second power supply I have is faulty somehow I wish there was a way to test out this mobo but I don’t have another 300 series motherboard lying around so not really sure what to do here

If this is a new build that hasn't been running before, it would seem the board is indeed the culprit. Not all that unusual to have a defective board. I've had my share.
Try splitting the 4+4 connector and just powering half of the 8-pin header. Then just the other half.

Lastly, try this. Remove the board and breadboard the system on an insulated surface. Connect just the CPU/cooler, monitor (iGPU), RAM, PSU. No KB or mouse or any other components. Start the system by momentarily shorting the two pins that the case's power button would connect to. See if it starts and produces a display.

 

[ottovonsanders]

I’ve built this rig in 2017 of holiday season so it’s about one-year-old and was running fine nothing wrong with it no signs of Blue screen of death or anything except for that power supply The fan on the psu was making a noise which probably was the bearings on it because it was a five Years old psu But stupidly enough that wasn’t the case I guess I just didn’t want to hassle taking it out of my case troubleshooting every component pain in my ass and I really didn’t wanna do that and in the end I ended up paying for It Who figures it would be the High-quality $140 motherboard. I tried the things you said but it’s still not working I’m guessing something Ruptured on the eight pin connectors I wonder if it was when I was running a game on 630 UHD that would make sense Though I wasn’t playing that game at the time I was playing it 1week ago befor this happened and after the game I was just Surfing the web, maybe that Contributed To its Demise anyway that’s what I get for getting a motherboard brand called Ass-rock