Alternate Framebuffer Drivers

With XenServer installed on a generic machine (AMD Ryzen custom box)  I have had to install a 3rd party GPU to enable visual output. I don't use this but I find that the machine crashes frequently (daily), I've traced it back to the fact that the GPU is overheating. Having swapped out the GPU with 2 others I had to try, it turns out that the default framebuffer setup doesn't activate any of the gpu cooling / throttling options (it runs the fan at full tilt for example, never throttling down). While I can appricaite most servers don't have external GPU's I wondered if there was a reason why the Dom0 is limited to only using the VesaFB. Done plenty of Goolging around and not really found anything useful. I don't want the card to be passed through to another device, I'd just like to be able to activate the on card controls which come in via alternate drivers.