Can x900 cartridges physically fit in other slots?

Yes. They fit in different slots. You just have to switch the chips.

best,
Walker

Are the 7900/9900 cartridges (the refillable ones from inkjetmall) physically compatible with different color slots? i.e. Could a yellow position cartridge be placed in a magenta slot and operate if the chip was swapped over?

Among other things, could be useful to have one or two spare empty cartridges on hand should anything fail, along with a full spare set of chips.

Thanks @walkerblackwell. What about the IJM cartridges for the 7700/9700? Are they physically interchangeable with the 7900/9900?