No, K6-X can work in TX motherboards. Highly out of spec, I might add (not spec'ed to run on regular S7). It requires a certain level of BIOS support, as above with the L1 cache, and other features. Most Socket 7 motherboards I know of don't go below 2.5V, so that's one problem. It's just a processor that's not fully supported - in a way, kinda like Thunderbirds in a KX133 system.