PC Processors

[Lea1945]

New AMD 5700X and ASAS B559-F motherboard will not start POST. Power connected and CPU fan runs, case fan runs, and RAM lights are on, so power is good to MB. Nothing connected to MB. Same result without RAM installed.     

[elstaci]

That processor, Ryzen 7 5700X is not listed on your Asus Motherboard CPU SUPPORT LIST even though Ryzen 5700 APUs are listed and Ryzen 5800X is listed: https://rog.asus.com/us/motherboards/rog-strix/rog-strix-b550-f-gaming-model/helpdesk_cpu

I suggest you open a Asus Support CHAT and ask them if your current BIOS supports the new Ryzen 7 5700X processor since it does support the 5700 series APUs and 5800 series processors.

To see if it is due to your processor being incompatible. Disconnect everything from your motherboard except the PSU & CPU.

Turn power on, The Motherboard's Trouble CPU LED Light should come on for a second and then turn off and the RAM LED light should come on.

If the CPU LED light stays on and doesn't turn off that indicates the processor failed the BIOS test and stopped the booting process.

If the CPU LED light turns off then install ONE RAM STICK on A2 DIMM Slot and see if the RAM LED light turns off and the VGA light turns on.

If the VGA LED light turn on then install the GPU and connect your Monitor and Mouse & Keyboard and see if it boots into BIOS or Windows.

EDIT: @ThunderBeaver  made a good point about the PSU Motherboard power cables. Make sure you have the CPU Power cable (6 or 8 Pin plug) connected otherwise it won't boot up.

[Lea1945]

I ran this test and the MB light stays on, as do the RAM lights. cPU  fan is running.

[elstaci]

Which Motherboard Trouble LED light is on?

Partial view of your motherboard's Layout from your manual showing the Trouble LED lights I am talking about:

[Lea1945]

The light that stays on is next to the large power plug. The power supply is a new EVGA 650BS. 

Nothing is plugged in. Results are negative without RAM or new 1030 card.

[ThunderBeaver]

Is that one of the EVGA slim line models?

If so that could be your entire problem.

A lot of reports about the EVGA 650 750 and 850 watt slim line versions have shown serious power stability issues.

[Lea1945]

I messed up the post, this is a 5600x. It os listed and also has a sticker that it is RYZEN 5000 ready.

The lights stay on on RAM and MB>\. I tried it with/without GT1030 or RAM.

[ThunderBeaver]

Can you get into BIOS and if so does it show all your hardware?

Make sure your MOBO is set to factory defaults save and exit.

What kind of storage boot device are you using?

If using an NVME device some MOBOs state that if your GPU covers one of the NVME slots to use the slot furthest from the GPU. 

What PSU are you using and what is its wattage output.

[elstaci]

If the Motherboard's Q-LED (Trouble) RAM Light is on that means either your have a defective RAM, Motherboard DIMM Slot or CPU.

Can you post the exact RAM Part number that you are using to see if it is listed on your Motherboard's QVL LIST for RAM MEMORY for the 5000 Series Processors or at the RAM Manufacturer's QVL List for your motherboard?

IF the RAM Trouble LED light is on that indicates the it failed the BIOS Test for your Memory. Could be not compatible or defective RAM Module or possibly defective DIMM SLot (Memory slot on Motherboard) or even a bad CPU.

The Q-LED for RAM will only come on if you have no RAM installed or if it fails the BIOS RAM test while booting up (POST).

[ThunderBeaver]

Try reseating all your internal power cables both on PSU and all hardware. 

Also ensure you have the right boot priority setup in your BIOS.

If installing OS from USB then make that number one if installing via DVD do the same with the disk drive.

Try changing SATA ports on your MOBO form your BOOT drive are replace the cable it may have just gone bad.

One power cord not seating properly can prevent a boot or post. I've found in the last 5 years PC's are getting very sensitive to power management and distribution.