3DMark Vantage:

3DMark® Vantage is the new industry standard PC gaming performance benchmark from Futuremark, newly designed for Windows Vista and DirectX10. It includes two new graphics tests, two new CPU tests, several new feature tests, and support for the latest hardware. 3DMark® Vantage is based on a completely new rendering engine, developed specifically to take full advantage of DirectX10, the new graphics API from Microsoft.  3DMark Vantage can also test your video card in several different ways. 

For the purposes of our bench, we will be testing with the Performance, High, and Extreme Presets.  Here are our results:

Vantage Performance:

In Vantage, the 4850 performs at 75.9% of the 4870 Toxic, and at 64.3% of the 4890 XXX edition.  Keep in mind, that at today's prices, the 4850 is 62% of the price of the 4870 and 56% of the price of the 4890.  This goes to show that the 4850 Vapor-X is an excellent value. 

Vantage High:

At the high preset, the 4850 performs at 68.6% of the 4870 Toxic, and at 56.78% of the 4890, again showing the value of the Vapor-X.

Vantage Extreme:

At Extreme, the 4850 performs at 67.4% of the 4870 Toxic, and 56.9% of the 4890.  This is right in line with the cost comparisons as well. 

3DMark06:

Futuremark's 3dMark06 has long been the go-to benchmarking tool when it comes to synthetic benchmarking.  Love it or hate it, there is no question that 3DMark06 has been the measuring stick of video card performance industry wide for several years.

I will be using Version 1.1.0 professional.  The free downloadable version can be found here.

In 3DMark06, the 4850 Vapor-X scores 76.2% of the 4870 Toxic and 66% of the 4890 XXX.