Hi, I'm trying to make an RSX out of GeForce 7900 for some performance evaluation. I can easily downclock memory to reach the bandwidth of RSX, but how could I disable ROPs (or just downclock them) to reach RSX fillrate (without affecting shader core of course)? Google found some discussion around here about this and that it might be present in some next version of RivaTuner, but I can't find anything like this in v2.01. Thanks!
I've reserved this thing for future, but I can give you some tip: you can control ROPs on 7900 series from the very first version of RT supporting this core. Some bits of pipe control register accessible via NVStrap can disable ROPs. That's everything I can say now, sorry.
But the whole thing about disabling ROPs is not as easy as disabling shaders? If I turn any bits off in byte 3 my machine won't boot while byte 4 has no effect...
Don't have such card installed to verify it right now, but it was not tricky, as far as I can remeber. As I can recall, there is 2-bit ROP control field. Just ensure that you don't disable _all_ bits at once. Doing the same for pixel pipes for example will also cause OS to hang.
Hmm... I have found that 2 bit control field (by comparing values on 7900 and 7400), but something strange happens... I can change those two bits, but when I click ok and restart machine and run RivaTuner again I can see bits enabled in binary representation of register and its bitmasks, but "Def:" and "Cur:" fields on top still display default values at apropriete positions for those two bits. Only "Tgt:" shows what it should be. So it's either that I have a problem with instrumented driver, or RivaTuner 2.01 is masking out actuall changes in EXACTLY those two bits?
RT is not masking anything and allows you to override all the bits you see in units config register controlled by NVStrap (of course, if the bits are not R/O hardwired with fuses (e.g. the pipe is fused to be protected from enabling)). If you're having problems with configuring NVStrap - you can always access units configuration registers (0x1540/0x1544) directly via command line /WR (WriteRegister) interface. But honestly, seeing lack of progress here, I won't recommend you doing that. Chip should be accessed directly only in case of full understanding.
