I think i had the same issue seen with one of my Geforce 6 series cards during a benchmark session.
It's a 6800 LE.
Core clock: 300 Mhz, RAM clock: 350 MHz=700 Mhz effective, 8 / 4 active pixel- and vertex shader.

Your XT has the same core, the clock speed can be different.

Don't remember exactly, but i think i have used two tools: RivaTuner for unlock, and PowerStrip for frequency overclock.

Here my 3d mark results (3DMARK 2001 SE):

6800LE (@300/700): 16291
6800LE (@370/750): 17366

6800LE (@12p/6v/300/700): 17331
6800LE (@12p/6v/350/750): 17522

Thanks,
But 3dMark2001se heavily relies on cpu also.
So you should specify which one you have.
Plus, you are telling me that powerstrip unlocked the frequencies?

Using the suggested Powerstrip method I was able to modify freq values.
But...

Chip cannot go over 350mhz, not a single mhz more.
Memory can be raised of 20mhz, nothing more, and it is strange.
hy5ds283222bfp-33 chips are rated for 300mhz and I am stuck around 200....

Using Nvflash to load a modified bios with some more volt (1.4v) is a no go as it won't access the bios...

This card is a mystery...

It could be the ram is being supplied a lower voltage with the lower speed. Does the data sheet for the ram list the operating voltage?

chrismeyer6 wrote on 2021-01-25, 13:14:

It could be the ram is being supplied a lower voltage with the lower speed. Does the data sheet for the ram list the operating voltage?

Probably,
But as said, nvflash is not able to access the bios modified with Nibitor.
Have you a specific version of nvflash to be used?