Virtual-Hideout posted a review on the ASUS 9800 GTX 512MB Graphics Card. Here's an excerpt:

The most obvious things that have been improved in the new 9800 graphics card line are the GPU thermal properties, noise, and overall weight. Under normal operations, all of the test cards were all equally quiet with the 9800 GTX generating just a little bit less noise. Even though the card is long enough to hang past the edge of the full sized ATX motherboard, the card is lighter than the 8800 GTS, but not quite as light as the 8800 GT and HD 3870.

When it comes to GPU heat, the EN9800GTX is a relatively cool running card. The average desktop temps while working is around 50 C and tops out around 60 C at it's highest point. The 8800 GTS averaged 55 C and topped out around 68 C which isn't bad either. Now compare the EN9800GTX to the 8800GTX in terms of temps. The 8800GTX has easily reached 80 to 90+ C at full load for quite a few users.

Prices for the 9800GTX range $300 to $350 for the stock frequency cards and the overclocked editions starting about $350 and up. The 8800 GTX are comparably priced with the limited Ultras pulling a $500 premium. That's a lot of money to get a few extra frames when the 9800GX2 is evenly priced with the Ultra.

The bottom line here is that the ASUS EN9800GTX is a much cooler graphics card that's capable of replacing the 8800 GTX in ASUS' line up. Should you run out and replace that 8800 GTX you already have? Not really. Performance between these two GTXs is a pretty even battle with the newer 9800 winning out a little. Those looking for the newest performance card that offers the best bang for buck are going to find the ASUS EN9800GTX to be a good option. The only thing that would make it an even better choice would be a lower price tag and a decently bundled video game. It's ASUS, so anything is possible.