I was running a 6900xt with SAM enabled no problems. Upgraded to the 7900 XTX and I can't enable it.
"Not Available"
CSM is disabled.
Above 4G enabled
ReSize Bar AUTO.
Ran a full DDU between GPU's
Motherboard is up to date.
Is it because I'm not using a 7900/7950 CPU with it?
"Not Available"....!
Check with this is if you are missing something:
https://www.amd.com/en/technologies/smart-access-memory
Figured it out... Somehow my chipset drivers vanished. Installed the latest version and it's all good to go.
AMD Radeon RX 7900 XTX and XT Smart Access Memory Performance - The FPS Review
They are showing settings here for How to enable Smart Access Memory....if it could help.
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I'm in the same situation you were. I currently have a R9 5950x and a RX 6900xt. Is it worth it to upgrade to the 7900 xtx?
Yes, I think you should. Most of my games at 3840x2160p would average 60-80fps but now with the 7900XTX I'm hitting 90-120fps. Much more of an improvement than when I went from a 2080ti to a 6900xt.
Re the difference in performance between a 6900 XT and a 7900 XTX see these weblinks from the Techpowerup review of the standard 7900 XTX
Average FPS
AMD Radeon RX 7900 XTX Review - Disrupting the RTX 4080 - Average FPS | TechPowerUp
Relative performance (%)
AMD Radeon RX 7900 XTX Review - Disrupting the RTX 4080 - Relative Performance | TechPowerUp
HTH
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