Question New AM5 build won't pass POST

[forestation]

Ryzen 7900
ASRock B650M Pro RS Wifi
g.skill Flare X 2x16GB DDR5 6000 CL30
EVGA 550W

Everything else is disconnected except the CPU cooler.

When posting, the CPU and DRAM lights stay a solid red.

Things I've done:
- Test the RAM sticks one at a time, in each slot
- Flashback to the latest BIOS
- Clear CMOS

A few possible clues (or maybe not?):
- The power supply seems to be delivering power normally to the fan at least
- The metal fins on the CPU cooler are cold to the touch; no power to CPU?
- When I daisy chained two case fans to the board, the stock rear fan spun normally, but the Arctic PWM PST fan would jitter for a moment when I turn on power but not actually spin

I'm at wit's end. Any suggestions?

 

[rgd1101]

model of this evga 500w?

 

[Misgar]

If you have XMP/EXPO memory overclocking enabled (6000) try setting it to off.

PC is more likely to boot up at JEDEC default RAM speed.

 

[forestation]

model of this evga 500w?

EVGA SuperNOVA 550 G3, 80 Plus Gold

Bought it a couple years ago, this is the first time using it.

I read about testing it by shorting the green pin to black/ground with a paper clip. I'll try that next.

Edit: G3, not GA.

 

[forestation]

If you have XMP/EXPO memory overclocking enabled (6000) try setting it to off.

PC is more likely to boot up at JEDEC default RAM speed.

I haven't been able to do anything with the board yet (other than flashback, which was successfull). It doesn't boot up or bring up the UEFI screen.

 

[forestation]

It turns out EVGA has a cap (like a CMOS jumper cap) to short the green wire for testing. I've done the test and the PSU fan did turn on. Days that mean the PSU is likely ok?

 

[lojikal]

Recheck your connections. Start with the 6 pin CPU connector. Additionally check of the CPU is seated correctly.

 

[forestation]

Well this is embarrassing. I didn't connect the CPU power cable! I've built systems before, but somehow thought the 20+4 connector of the ATX cable included "+4" for a CPU.

After connecting the cable, system booted up speedily and I was able to run the advertised EXPO profile. Happy as a 6 year old on Christmas morning. Appreciate the help!