Just dropping this here as someone was asking about it, especially when using older drivers.
Using W11 driver 546.65. Just a simple power limit increase to max 300W, set for 250W and unlocking of Xbar and Sys OCing. Default Xbar and Sys clocks are pretty close to Gpc clock so don't really see much when increasing them so dropped them 500MHz to show it's working before applying +200MHz. Personally not really worth it for me as can get a similar result without the vbios override, more useful for recent cards I think.
A first place result without vbios override https://www.3dmark.com/sb/517581
PS Not working for Pascal cards.