The signature series has some advantages, some special support line when you call, higher clocks of course. The only difference besides money would be the additional memory on the GTX and huge heatsink. Either one of those have enough power and cooling to keep you happy. Oh and I'd advise against Always Technically Inept or ATI as some call them. Seems someone outside of ATI has developed some Omega brand drivers for the ATI cards and they out preform what ATI's own can code, think that tells the story pretty well.