Old PC`s and Mach3

[Ger21]

My take is that anyone looking to buy a UC400ETH should buy the UC300ETH. The price difference is fairly small, and the UC300ETH gives you a lot more I/O, plus analog inputs and outputs.
It really makes no sense to buy the UC400ETH, except as a step up from the UC100, unless you know you'll never use the extra I/O or analog I/O.
Performance between the UC300ETH and UC400ETH is the same.

If you go the UC300ETH route, I highly recommend the UB-1 breakout board from CNC Room. This breakout board eliminates the need for the 5LPT motherboard that the UC300ETH is normally mounted to, which saves about $40. You can buy the UC300ETH with the UB-1 as a package. http://www.cncroom.com/interface-cards/uc300eth-ub1

If you need all 5 ports, CNC Room just came out with a 2 port daughterboard for the UB1 as well.