Power Consumption & Temperatures
The power consumption levels of both GeForce GTX cards are impressive when at idle. The GeForce GTX 280 uses significantly less power than the Radeon HD 4870, and only slightly more than the Radeon HD 4850.
Load results tell a completely different story. Under this scenario the Radeon HD 4850 uses considerably less power than both GeForce GTX graphics cards. Even the Radeon HD 4870 makes up for the previous lackluster result using less power than the GeForce GTX 260. You will also notice how both GeForce GTX graphics cards break the 300 watt barrier for overall system power consumption.
Mirroring the impressive idle power consumption results, the idle temperature results of both GeForce GTX cards look very promising.
While the GeForce GTX 260/GTX 280 idle at 43/45 degrees, the Radeon HD 4850/4870 idle at 71/74 degrees, which is unacceptable. Under load the Radeon HD 4850/4870 cards don't get much better, hitting 89/82 degrees respectively (the slower card uses a single-slot cooler design versus the 4870's dual-slot cooler).
In comparison, the GeForce GTX 280 reached just 78 degrees, while the GeForce GTX 260 leveled off at 72 degrees. Both GeForce GTX cards use dual-slot coolers, and this is expected from all products that follow the manufacturer's reference design (90+% of all cards shipping today).