NVIDIA 400M: DX11 Top to Bottom Solutions Now Availableby Jarred Walton on September 3, 2010 12:02 AM EST
Performance and Mainstream 400M
After the high-end parts, the drop in performance can become precipitous. This has been particularly bad for AMD GPUs, where the drop from Mobility 5800 series down to the 5700 and 5600 parts often means less than half the performance. NVIDIA has had a few more upper-midrange parts floating around, though, and that looks to continue.
|NVIDIA Performance and Mainstream 400M Specifications|
|GeForce GT 445M||GeForce GT 435M||GeForce GT 425M||GeForce GT 420M||GeForce GT 415M|
|Graphics Clock (MHz)||590||650||560||500||500|
|Processor Clock (MHz)||1180||1300||1120||1000||1000|
|Memory Clock (MHZ)||800/1250||800||800||800||800|
|Standard Memory Configuration||DDR3/GDDR5||DDR3||DDR3||DDR3||DDR3|
|Memory Interface Width||128/192-bit||128-bit||128-bit||128-bit||128-bit|
|Memory Bandwidth (GB/sec)||25.6/60.0||25.6||25.6||25.6||25.6|
First, you'll notice that none of these "Performance and Mainstream" parts supports SLI. That's hardly surprising, as SLI with lower-end mobile GPUs has never been our recommended approach. First get to the high-end for performance reasons, and then worry about SLI. Other than that limitation, all of these parts have the same features as the faster parts on the previous page.
The new GT 445M is the first part to come with split specifications. Given the option for 128-bit and 192-bit bus widths, it appears the 445M will use the full GF106 memory controller for the higher bandwidth version and cut off one of the 64-bit interfaces for the low bandwidth model. Many of our gaming results have looked bandwidth limited, so we'd definitely recommend going for the GDDR5 192-bit model if possible, but that will be up to the notebook manufacturers. 445M looks to compete in a similar space as 460M with the higher bandwidth model, but it cuts computational power quite a bit at roughly two-thirds of the 460M. The difficulty here is that 445M can be either substantially faster than some of the older parts, or if you get the 128-bit DDR3 model you're suddenly cut down to less than half the bandwidth. Heavy use of shaders, tessellation, etc. might make the lack of bandwidth less painful, but without hardware and future games it's difficult to say how things will play out.
The 435M is a more straightforward replacement of GT 335M. (Did someone ask for a remake of M11x with a DX11 GPU? Hopefully they can do something about the LCD this time around….) 335M has 72 cores at 1080MHz, with 34.1GB/s of bandwidth. Unless something changes, 435M will actually have less bandwidth but substantially more computational power—60% more to be exact (plus architectural changes, obviously). This is a pattern that holds throughout the 400M lineup, so NVIDIA appears to be betting heavily that shader performance rather than bandwidth will become important.
Along with the 435M come several more GPUs; the 425M and 420M have the same bandwidth and core counts, but lower core/shader clocks. This is similar to the current 325M/330M, which have 48 cores but the same amount of bandwidth as the 335M. Even the lowest 420M has around 25% more compute power than 335M, but they all have less bandwidth. It would have been nice to see a move to GDDR5 on more of the Performance and Mainstream parts, as that would have improved overall performance substantially.
Finally, wrapping up the low end we have the GT 415M. Here we can actually see something to celebrate, since the previous generation parts largely consisted of 16 core models with a 64-bit bus (i.e. the G 310M). On the compute side, we're looking at nearly twice the power of the G 310M. Bandwidth also gets a kick in the pants, going from 12.8GB/s to 25.6GB/s. In short, our entry-level mobile GPUs just doubled their performance. Note also that if NVIDIA wanted to cuts things down even further, they'd need to make yet another chip (i.e. GF110), since 48 cores is a single SM. Most likely, for anything below GT 415M they'll just continue to sell their older 300M parts.