MSI B450 Gaming plus max not detecting Zotac RTX 1660

Hardware
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1

I have an older MSI B450 Gaming plus max motherboard that worked with a number of GPUs in the past, including 2060, 3090, GT730, A4000, 3080 and 3080 TI

Today i got a ZOTAC RTX 1660 for it, unfortunately the MSI B450 Gaming Plus max does not detect the 1660. Tested the 1660 on other motherboards and it works perfectly.

Using the same power connectors and slots as have in the past but cannot get the motherboard to detect this particular GPU. Today i tested the motherboard with a 3090 and GT710. Also tested the GPU on a threadripper workstation and it works!..

I have also tried using both x16 slots-- both work with other cards, but neither detect the 1660.

Also did a dual GPU test using the GT710, which showed the bios not detecting the 1660 when placed in either x16 slot.

any ideas whats happening here and how to fix it?

2

Just to rule out the obvious… You have updated the BIOS to the latest version? Check Zotac website too, sometimes they do have BIOS updates for graphics cards.