Need help regarding ram xmp

[Mahir]

so a few days ago i bought a 8gb stick of corsair vengeance lpx ram at 3200mhz
and when i went into my bios to turn on the xmp i saw that it did not support xmp and also when i manually set the speeds to 3200mhz but on boot it would say that overclocking failed.
i have another stick of ram which does support xmp and when i use both of them together only then can i enable xmp. i cannot enable it when using the vengeance ram on its own.
i asked the guy whom i bought it from about this issue and he said he never enabled the xmp cause he didnt know what it was and this ram was pretty old. like the box says intel 7th gen supported that old.
i dont have any problems right now since im using 2 sticks and i can enable the xmp, but i really wanna know what i can do to use this ram at its rated speeds on its own.
note that the other stick of ram i have is from a different brand so the rams arent same. and after enabling xmp i get 3200mhz on both of them.