MAC PRO 2019 GPU DIE 1 / 2 Temp sensors are faulty, resulting in max Fan Speed as safety mode

Mac Pro 2019 / MPX Radeon 580X.

Recently I experienced a sudden burst of the Bottom Fan on my Mac Pro. After a diagnostic in a certified repair shop, and after trying to analyse the problem myself with ** PRO and iScan, it's clear now that both GPU DIE 1 & 2 are faulty, because no values come out of those 2 sensors ( very randomly they get back to work, and fans stop ).

My question is : Are those sensors located on the GPU itself or on the motherboard ? I want to know if by swapping the faulty GPU with a new one it will resolve this temp sensors problems.

Also, what's the cost for a new MPX 580 card ? I struggled finding consistant information on the web

Thanks