As John mentioned, it has a lot to do with what has been tested previously.
I had a very old graphics adapter (now removed) in my p615 - which worked fine as long as I booted in 32-bit mode. Once I switched to 64-bit AIX still saw the card, but could not use it.
I did some searching, as I knew there had to be documents on all of this. Links are below.
re: GTX4000/GTX6000:
The POWER GXT4000P and POWER GXT6000P graphics adapters are single card
adapters that attach to your system unit in a PCI bus slot. The PCI bus interface
provides 64 bit, 66MHz (50MHz systems) and bus master support and requires 3.3 volt
power. These adapters provide 3D graphics acceleration. Connection to the video
monitor is made through a DVI (Digital Video Interface) connector.re: GTX3000
The POWER GXT3000P 3D graphics adapter is a mid-range double-wide single card
adapter that attaches to your system unit in a PCI bus 64- or 32-bit slot. This
adapter provides 3D graphics acceleration.
And then finally your model PCI information:
PCI Slot 5 (32-bit)
PCI Slot 4 (32-bit)
PCI Slot 3 (32-bit)
PCI Slot 2 (64-bit)
PCI Slot 1 (64-bit)It looks as if the 4000/6000 cards might be useable as you have 64-bit slots. What I have not been able to determine is if the power from the 64-bit slots is correct. I leave that to you.
The relevant links for you are:
RS/6000 7043 Model 260 Hardware InformationRS/6000 7043 Model 260 Service Guide RS/6000 PCI Adapter ReferencePOWER GXT3000P Graphics AdapterPOWER GXT4000P and POWER GXT6000P Graphics Adapter