Now this is surprising. Although Zotac's Amp Edition GTX 480 offers a 56MHz overclock, it actually draws less power than the reference design GTX 480. In fact, we found Zotac's product required 48W less under load conditions than the stock GTX 480 we have on hand.
The cooling power of the triple slot cooler found on the Amp Edition GTX 480 is outstanding. Remarkably, it comes within one degree of matching the temps we recorded for Gigabyte's Super OC HD 5870. When compared to a the reference design GTX 480, the Amp Edition ran 27 degrees cooler under load and 10 degrees lower during idle.