New Build No Power - Bad Power Supply?

[acordeon]

Just got done assembling a brand new Ryzen build. Components listed below. System shows no signs of life at all - no LEDs, no beeps, no fans spinning anywhere, including on the PSU (which is a brand-new Seasonic Focus Plus).

I suspected either a problem w/ the power switch on the case, or a bad PSU. I had an old PSU tester lying around (the kind w/ the LEDs). So I plugged the PSU in to that, and result is that only the +5VSB light is on - all the rest are off - https://imgur.com/FpxUQ1i. That means a bad PSU, right? Is there any scenario in which it doesn't mean it's DOA?

I do want to make sure I have the cables connected properly to the PSU. This is my first time using a modular PSU, and the instructions in the Seasonic manual were pretty much nonexistent. I have the 18 bin mobo cable plugged in where it says M/B, along w/ the smaller cable labelled BJ23. Next to that I have the CPU cable plugged in. That's it. https://imgur.com/SblVKBJ

Should I try to jump start the PSU? (https://www.youtube.com/watch?v=Ea1dcJ0QyAE). My understanding is that the tester should provide the circuit that the PSU needs to run, so I haven't tried this.

I do have another much older desktop, which has a smaller, non-modular PSU. It's 380W, and pcpartpicker rates my system as 274W. Should I try using my old PSU in the new system to see if I can get it to boot? Is there any scenario in which one of my new components could have fried the PSU? Don't want to fry the old one too. And conversely, any reason to be cautious using an older PSU with a newer system?

Thanks much!

CPU: AMD - Ryzen 3 1300X 3.5GHz Quad-Core Processor
Motherboard: MSI - B350 PC MATE ATX AM4 Motherboard
Memory: G.Skill - Flare X Series 16GB (2 x 8GB) DDR4-3200 Memory
Storage: Samsung - 960 EVO 250GB M.2-2280 Solid State Drive
Video Card: Palit - GeForce GTX 1050 Ti 4GB KalmX Video Card
Case: Fractal Design - Define S ATX Mid Tower Case
Power Supply: SeaSonic - FOCUS Plus Gold 550W 80+ Gold Certified Fully-Modular ATX Power Supply
Case Fan: Noctua - NF-A15 PWM 140mm Fan

 

[mazboy]

'twer me, I'd remove the discreet GPU from your new build, and connect that old PSU to the motherboard and see what happens. You obviously won't have video, but you should get POST beeps from the motherboard speaker (you did hook that up, right?), and you should get motherboard LEDs, case/CPU fans and such whirring and lighting up. If this works, you've pretty much got a DOA PSU and need to RMA it back to whomever you got it from.

It's hard for me to imagine that you assemble the computer in a manner that would fry the PSU.

 

[acordeon]

Good advice. Looks like the PSU is indeed DOA. First plugged the old PSU into my tester to make sure the tester works. Got all the expected lights. Then hooked it up to the new build as you suggested, and got post and fans. Thanks for the help!