670E Steel Legend- 4090 wont power

just put my system together with all new parts, and it all works and boots, video with onboard till I put my 4090 in. Recommended Coursair HX1200 PSU, all 4 Connectors connected. I plug it in and hook power to Card and then it won't power on (still led's on board but no troubleshoot lights, the board is not starting, no fans) I unplug power with the card in, powers right up. Double-checked power connections. it's a NEW Zotech Amp Extreme. Something in BIOS I am missing?, been a long time since I built a system from scratch. did clear bios and it's updated to the current one from the Asrock website. since everything works till I put a 4090 card in I am leaning towards a bad card maybe, Just had a 3090 fail on my old rig, can I get this unlucky? (machine is on a UPS so its not some odd power issue)

I'm pretty sure that clok1966 is talking about the GPU power connector, not motherboard. I'm assuming that giant RTX 4090 is using the new 12+4 pin power connector, and you're using an adapter that takes four separate 8-pin connectors from the power supply.

The new 12+4 pin connector has a bad reputation. Make sure it's REALLY REALLY IN THERE.

If you have another GPU, maybe try that, if only to eliminate motherboard/CPU as culprit.

Looks like dead short check with multimeter pins on adapter and later GPU.

thanks for suggestions, I have resolved it. was a 3rd party 90 degree 4090 connector.
SYBECHATF RTX 4090 4080 4070TI 3090TI 16Pin(12+4) to 4x8Pin Cable with 90 Degree 12VHPWR Connector,for Corsair

Used the included STIFF connector and it all works. I should have done that right away, poor troubleshooting by me. But it was a new build and I did not want to use that horrible ugly one (pride).