The 5950 Ultra takes a bow
In case you've been living under a rock or, heaven forbid, away from the computer screen for a few months, I should mention that NVIDIA's previous top-end graphics card was the GeForce FX 5900 Ultra. As you might imagine, the 5950 Ultra replaces the 5900 Ultra, which makes sense, because the 5950 Ultra is just an amped-up version of the 5900 Ultra. The NV38 GPU core on the 5950 Ultra is a tweaked version of the NV35 core found in the 5900 Ultra. Specifically, NVIDIA and its manufacturing partner, TSMC, have improved the NV38 through changes to the chip manufacturing process, including the use of a low-k dielectric to help improve clock speeds. As a result, the NV38 runs at 475MHz, up 25MHz from the 5900 Ultra.
Beyond the manufacturing changes, there's not much new to report in the NV38 chip proper. The GPU is still a four-pipe design with two texture units per pipe, and beyond that, much of the GPU's internal architecture remains a bit of a mystery. The GeForce FX 5950 Ultra card, however, is rather different from its predecessor. The first thing you'll likely notice is the new cooler, with its larger blower enclosed in a plastic shroud that pulls air in via a PCI slot opening and blows it across a heatsink on the NV38 chip.
You've heard of Abit's Outside Thermal Exhaust System, or OTES. Now meet OTIS, the Outside Thermal Induction System. Not that NVIDIA calls it that, of course. OTIS was the town drunk.
NVIDIA claims the 5950 Ultra's cooler is quieter than the one on the GeForce FX 5900 Ultra, and I suppose that's true in most cases. I wasn't displeased at all, though, by the noise levels of the 5900 Ultra cooler. (Both seem whisper quiet compared to the Dustbuster appendage on the old 5800 Ultra cards.) The 5950's larger blower should move higher air volumes without creating as much noise, and this cooler design definitely channels air with more discipline. I am puzzled, however, by NVIDIA's decision to use a simple metal plate to pull heat away from the memory chips on the front of the card. The 5900 Ultra's memory heatsinks were more... heatsinky. The 5950 Ultra reference card was perfectly stable in my testing, but that green plate got scary hot. Then again, most graphics cards that cost upwards of 300 bucks are scary hot most of the time.
The most notable improvement to the 5950 Ultra card isn't the most visible, however. The biggest change is the faster clock rate on the DDR graphics memory, up 50MHz from 425MHz to 475MHzor, effectively, from 850MHz to 950MHz, once you factor in the double data rate action. That means memory bandwidth is up from 27.2GB/s to 30.4GB/swell above the Radeon 9800 XT's comparatively wimpy 23.2GB/s.
Incidentally, the 5950 Ultra won't have a non-Ultra "GeForce FX 5950" counterpart. Instead, the current GeForce FX 5900 will continue as NVIDIA's offering at the $299 price point.