[SOLVED] New PC build won't POST. No display. No error codes

[TheJezter]

I understand "no display on first boot" is a common problem with many issues. But I haven't found any threads with my exact issues.
So I built a new PC yesterday. I'm not new at building computers, but not advanced either (I've built maybe 6 or 7 of them so far). This new one looked to be going great for the first few seconds when I turned it on, but then there was no display. I thought it could be an issue with the monitor or cable so I tried a few combinations of hdmi, displayport, and monitors. Nothing worked. Then I realised the GPU isn't even turning on. Normally when you boot a pc the GPU fans spin for a sec. This one wasn't at all. I tried a different GPU and different pcie power cables. No change. I've tried reseating RAM and cpu. Nothing. Tried only one RAM stick. Still nothing. I plugged in a motherboard speaker to hear beeps. No beeps at all. And the on-board diagnostic Q-led also has no codes showing. This leads me to believe it isn't even reaching POST. Weird because all lights come on: Mobo, Ram, fans. Cpu radiator fans run fine. Pc turns on with power button, but doesn't turn off with it (thought thst was kinda weird).

Build is:
-Asus TUF Gaming B550M-Zaku (Wi-Fi) m-ATX
-AMD Ryzen 5 5600X Vermeer
-G.SKILL Trident Z Neo (For AMD Ryzen) Series 16GB (2 x 8GB) 288-Pin RGB DDR4 SDRAM DDR4 3600
-Gigabyte Gv-N1660OC-6GD Geforce GTX 1660 OC 6G
-Thermaltake Toughpower Grand RGB 850W Smart Zero Fan SLI/CrossFire Ready Continuous Power ATX12V v2.4 / EPS v2.92 80 PLUS GOLD Certified Full Modular Power Supply PS-TPG-0850FPCGUS-R
-CORSAIR iCUE H100i RGB PRO XT, 240mm Radiator
-SAMSUNG 970 EVO PLUS M.2 2280 1TB PCIe Gen 3.0 x4, NVMe 1.3 V-NAND 3-bit MLC Internal Solid State Drive (SSD) MZ-V7S1T0B/AM

 

[General Kenobi]

I understand "no display on first boot" is a common problem with many issues. But I haven't found any threads with my exact issues.
So I built a new PC yesterday. I'm not new at building computers, but not advanced either (I've built maybe 6 or 7 of them so far). This new one looked to be going great for the first few seconds when I turned it on, but then there was no display. I thought it could be an issue with the monitor or cable so I tried a few combinations of hdmi, displayport, and monitors. Nothing worked. Then I realised the GPU isn't even turning on. Normally when you boot a pc the GPU fans spin for a sec. This one wasn't at all. I tried a different GPU and different pcie power cables. No change. I've tried reseating RAM and cpu. Nothing. Tried only one RAM stick. Still nothing. I plugged in a motherboard speaker to hear beeps. No beeps at all. And the on-board diagnostic Q-led also has no codes showing. This leads me to believe it isn't even reaching POST. Weird because all lights come on: Mobo, Ram, fans. Cpu radiator fans run fine. Pc turns on with power button, but doesn't turn off with it (thought thst was kinda weird).

Build is:
-Asus TUF Gaming B550M-Zaku (Wi-Fi) m-ATX
-AMD Ryzen 5 5600X Vermeer
-G.SKILL Trident Z Neo (For AMD Ryzen) Series 16GB (2 x 8GB) 288-Pin RGB DDR4 SDRAM DDR4 3600
-Gigabyte Gv-N1660OC-6GD Geforce GTX 1660 OC 6G
-Thermaltake Toughpower Grand RGB 850W Smart Zero Fan SLI/CrossFire Ready Continuous Power ATX12V v2.4 / EPS v2.92 80 PLUS GOLD Certified Full Modular Power Supply PS-TPG-0850FPCGUS-R
-CORSAIR iCUE H100i RGB PRO XT, 240mm Radiator
-SAMSUNG 970 EVO PLUS M.2 2280 1TB PCIe Gen 3.0 x4, NVMe 1.3 V-NAND 3-bit MLC Internal Solid State Drive (SSD) MZ-V7S1T0B/AM

Hello there!!
Im helping a user with the same issue and its also with Asus Mobo, id suggest booting your pc without ram to hear the beep code moreover after that try to boot with minimal parts i.e with cpu, ram and GPU only, disconnect every drives and usb devices except keys and mouse.
You can do also try the following

[Motherboard] Troubleshooting - No Power/No Boot/No Display | Official Support | ASUS Global

 

[alexbirdie]

You connected the 8-pin-CPU-PWR, too?

If yes, then looks 1. damaged PSU and/ir 2. damaged MB.