Zenith II Extreme Alpha and Astral RTX 5090 32GB - No Video Detected on post.

[Visumax]

Installed new Asus Astral RTX 5090 36GB DDR7 video card into my Asus Zenith II Extreme Alpha. When the system boots, the motherboard does not detect any video on post. Running latest 2402 BIOS. I have tried the card in multiple slots. Tried the PCIe Gen 3 and Gen4 setting. Tried Legacy OPROM from UEFI. Tested on an old Dell monitor with DVI 1.4 and HDMI. Reset the CMOS. Mobo Q-led displays the white led for VGA issue. Get the standard 1 long and 3 short beeps for no VGA detected but the system does get to the Windows log on screen because the systems RGB set to my setting - I just have no video 

When I drop back in my Asus STRIX 3080 - No problem. System operates as normal.

Specs: Stable - No overclocking - Water cooled

• BIOS 2402 8/12/2025
• AMD 3970x Threadripper
• NVMe Force MP600 2GB x2
• Samsung SSD 500GB x 1
• Seagate EXO 20TB x 3
• 128GB GSKILL F4-3600C18-32GTZR DDR 4 2666MHZ
• Thermaltake Toughpower PF1 1200W
• Strix RTX3080 10GB 

Looking for any other ideas because I don't know what else to try except to return the 5090?

[Nate152]

Hello Visumax

With the Thermaltake Toughpower PF1 1200W psu, I imagine you're using the 4 x 8-pin to 12VHPWR adapter cable.

Make sure you're using 4 separate pcie power cables.

[Visumax]

I do have 4 PCIe cables coming from my power supply and plugged into the 4 on the ASUS adapter that came with the 5090. The RED LED plug on the card goes out when I power the system so, I am assuming the power to the 5090 is good. I did not think about it but I guess I could still put a meter on it and check the voltage? Just need to find a pin out spec on the Asus adapter. Also thought about replacing the PSU for a 1200 ATX 3.1?

[Nate152]

Thank you

I came across an Nvidia thread where a few were having the same issue but with an RTX 5080. It seems setting the link speed to Gen 2 worked for most.

Click view all replies. - Issue with RTX 5080 and ASUS Zenith Extreme Alpha | NVIDIA GeForce Forums

[Visumax]

Thanks for the reply Nate. I tried GEN 2 without any luck. I also installed the 2102 on my second BIOS just to see if an early version would make a difference. Tried enabling CSM with different configs, setting 4G and enabling resize bar in the bios. I even metered all the pin from the power supply and up through the adapter that comes with the card- all solid at 12.10v. I have built a lot of systems around the ASUS platform over the years and have never had such a headache especially with an Asus video card. Asus high end mobo...Asus high end video card  - there should not be these kind of problems to display video. Ironically I did not by this card for video games but LLM inferencing.  I am open to any and all ideas or additional suggestions on what else I could try?

[Visumax]

Just a follow-up -  bad RTX5090. Sent it back to retailer for replacement and got the new card and system booted w/ video and w/out issue.