NVIDIA GeForce2 MX 400 64MB

The Chip

It is no surprise that the GeForce2 MX 400 is based off the original GeForce2 MX. Before we get to what has changed, let's recap what we saw in the GeForce2 MX.

The GeForce2 MX core is based off of a crippled version of the GeForce2 GTS core. In order to separate the high-end part from the lower-end one, NVIDIA choose to limit the power of the GeForce2 MX in three ways.

First, NVIDIA cut the number of rendering pipelines in half from what is present on the GeForce2 GTS. The GeForce2 MX features only two of the GTS's four rendering pipelines, each capable of processing two texels per clock. This leaves the GeForce2 MX with half the fill rate of the GeForce2 GTS, given the same core clock speed.

The second thorn NVIDIA lodged in the GeForce2 MX's side was the use of a 128-bit SDR or 64-bit DDR memory bus. Unlike the GeForce2 GTS, which uses a 128-bit DDR memory, the GeForce2 MX is left with half the memory bandwidth of the GeForce2 GTS. As we proved in our Overclocking the GeForce2 GTS guide, the GTS is already memory bandwidth limited with its 128-bit DDR memory bus. It was therefore no surprise that the cutting of available memory bandwidth put a huge damper on the GeForce2 MX's performance. We showed in our Overclocking the GeForce2 MX guide that while increasing core speed provided almost no increase in gaming performance, increasing the memory clock speed resulted in up to a 30% performance gain.

The final handicap that the GeForce2 MX was given was a decrease in the core clock compared to the GeForce2 GTS. The GeForce2 MX comes clocked 25 MHz slower than the more powerful GTS. This leaves the core operating at 175 MHz, a speed which we knew already pushed the limits of the MX's memory bandwidth.

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So, of all areas the GeForce2 MX could improve, guess which handicap gets removed in the GeForce2 MX 400 incarnation. No, NVIDIA did not choose change the core in order to increase the rendering pipeline and NVIDIA surely did not choose to pull the GeForce2 MX's largest thorn, the meager 128-bit SDR bus. Instead, the GeForce2 MX 400 improves upon the original GeForce2 MX in only one aspect: core clock speed.

That is right, the GeForce2 MX 400 is identical to the original GeForce2 MX except for the clock speed it comes shipped at. It was no secret that the original GeForce2 MX could easily reach higher clock speeds with little effort. The reference design of the GeForce2 MX does not call for any form of cooling, active or passive, and we quickly learned in the lab that slapping a heatsink and fan onto nearly any GeForce2 MX would result in the ability to overclock to at least the 200 MHz speed, if not more. In fact, even without any form of cooling, the cards would typically be able to clock near the 200 MHz mark. It is therefore no surprise that the new shipping clock speed on the GeForce2 MX 400 is not a single MHz more than 200 MHz. This places it right up to the clock speed of the GeForce2 GTS and increases the megapixel count from 350 million pixels per second to 400 million pixels per second (or 700 million texels per second to 800 million texels per second).

With two new chips, each bearing the GeForce2 MX name, and one original GeForce2 MX, things are bound to get a bit confusing. The table below should help ease that confusion.