Question Bad motherboard? Loses power with CPU installed.

[anvoice]

Hi, I posted this general question in "Systems" earlier but it evolved slightly along the way into a motherboard issue, so wanted to try here.

I have an Asus Rog Crosshair Hero VII wifi motherboard that behaves strangely. When connected to a power supply, after I flip the PSU's rocker in the on position, the RGB lighting and power button on the motherboard light up normally. However, after I install the CPU, when I flip the PSU rocker I get a blink of red on the power button, then nothing. However, before I benched this system I did successfully manage to start it despite the LEDs being off on the motherboard: when powered on either via the motherboard start button or the case power button, it would start up, shut off briefly, then turn on again and appear to work fine afterward. I tried this with two different compatible CPUs: same behavior, both CPUs are brand new and have no bent pins as far as I can tell. I also tried 2 different PSUs.

At this point the motherboard benched (I even removed the back CPU cooler bracket to make sure there are no shorts there, although it has a plastic spacer layer anyway) and no matter what combination of components I try, the CPU being installed causes the quick flash on the motherboard, then nothing. Do I have a bad motherboard (it was an open box item)? Advice is greatly appreciated, I've been stuck on this for days.

Hardware:
motherboard: Asus ROG Crosshair Hero VII wifi
CPU: Ryzen 2700X (tried with 2200G too)
CPU cooler: stock Wraith cooler
GPU: Gigabyte G1 GTX 1070
RAM: G-Skill Ripjaws V Series 32Gb (2x16) at 3200MHz
Storage: 2x PM981 512Gb NVME drives
PSU: Corsair CX450 (450W PSU)
Case: Phanteks Enthoo Pro M Mid tower case
5x Noctua NF-14A PWM fans

 

[cin19]

Hardware:
motherboard: Asus ROG Crosshair Hero VII wifi
CPU: Ryzen 2700X (tried with 2200G too)
CPU cooler: stock Wraith cooler
GPU: Gigabyte G1 GTX 1070
RAM: G-Skill Ripjaws V Series 32Gb (2x16) at 3200MHz
Storage: 2x PM981 512Gb NVME drives
PSU: Corsair CX450 (450W PSU)
Case: Phanteks Enthoo Pro M Mid tower case
5x Noctua NF-14A PWM fans

Get the better PSU, the cx 450 can't handle your PC with gtx1070.
You can try this troubleshooting, before buy the new PSU, if you want.

How To - Bench it - Troubleshooting

When All Else Fails - Bench It Let's start by looking at the mobo, is it installed in the case? If so make sure all mounting holes that can be used are used (normally six to nine) and have a standoff and screw used, no screwing directly to the case, need a standoff in each, otherwise mobo can...

forums.tomshardware.com

 

[anvoice]

Get the better PSU, the cx 450 can't handle your PC with gtx1070.
You can try this troubleshooting, before buy the new PSU, if you want.

How To - Bench it - Troubleshooting

When All Else Fails - Bench It Let's start by looking at the mobo, is it installed in the case? If so make sure all mounting holes that can be used are used (normally six to nine) and have a standoff and screw used, no screwing directly to the case, need a standoff in each, otherwise mobo can...

forums.tomshardware.com

Hi, thanks for your reply. As mentioned, the motherboard is benched at this point: all I have is the motherboard itself, with the CPU and the 24pin plus 9pin connectors. No GPU, no RAM. In that state, flipping the PSU rocker to on gives the board LEDs power. If I install the CPU though (tried 2 good CPUs), the board LED just blinks once when the PSU rocker is flipped, then goes dark.

As far as PSU goes, I tried 2 different PSUs, both with same result. Also, I have a new higher wattage PSU in the mail, was just testing with what I have.

 

[cin19]

Try this: ryzen 3 2200g, cpu cooler, no RAM, no boot device, no gtx1070, clean the CMOS, use the cx 450 PSU and the AMD onboard igpu. After that boot the PC, if you get the same result, no boot, no display, if you know the 2200g is fine, I will say the MB has problem.

 

[anvoice]

Try this: ryzen 3 2200g, cpu cooler, no RAM, no boot device, no gtx1070, clean the CMOS, use the cx 450 PSU and the AMD onboard igpu. After that boot the PC, if you get the same result, no boot, no display, if you know the 2200g is fine, I will say the MB has problem.

Tried this exactly as you suggested. It does not boot (Q-code 0d, which the manual says is reserved for future AMI SEC code errors), presumably because there is no ram or bootable devices. I then added a bootable drive and RAM and it now boots.

Note that the problem isn't that the computer doesn't turn on at all, it's that the motherboard power seems to go out with CPU installed. I don't know if it's going to fail altogether in the future, when I can't return the motherboard anymore.

So I guess a simple way to address this is: can anyone with a Crosshair VII Hero or similar motherboard confirm whether in your system, the LED lighting stays on when the PSU rocker switch is pressed? Or does the power button just blink once and turn off? If that's normal behavior, I can deal with it.