Apr 3, 2009 1:36 PM | 3 Comments

If only graphics chips were simpler. Nathan Taylor tries to keep track of the endless graphics chips released by AMD, Nvidia and Intel.

Trying to figure out graphics chips makes understanding CPUs model seem easy, and each vendor seems to want to try every permutation of memory, clock speed, bus bandwidth and shader unit numbers available, resulting in roughly a million different chips on the market at any one time, many of which differ only in the nuances.

Take the vendors’ newest releases: AMD first announced the Radeon HD 4890; Nvidia quickly countered with its GeForce GTX 275. Both parts landed in the hands of reviewers this week.

These new chips are not the highest performing parts from either vendor – that title goes to Nvidia’s GeForce GTX 295 and AMD Radeon HD 4870 X2, dual GPU chips both.

They’re designed to fill in a price point for both AMD and Nvidia, and don’t contain anything really new. This is especially true of the GeForce GTX 275, which is so similar to the 285 that I don’t know why Nvidia bothered.

The chips – ATI Radeon HD 4890
The Radeon HD 4890 is essentially a higher-clocked 4870. It technically boasts a new core, the RV790, but the architectural improvements are mostly designed to enable higher clock speeds rather than deliver more power per clock (as an aside, Tom’s Hardware is reporting that the improvements also make it a much better overclocker’s chip).

Compared to the HD 4870, the core of the processor is 100MHz faster (850MHz in the 4890 vs 750MHz in the 4870) and the memory is 75MHz faster (975MHz vs 900MHz).

That clock speed increase gives you a relatively linear improvement over the 4870, but it still can’t match the integrated SLI performance of the 4870 X2. Of course, it probably won’t be long before we see an ‘X2’ version of the Radeon HD 4890, which, like the 4870 X2 will be a dual GPU solution on a single board.

The chips – Nvidia GeForce GTX 275

The GeForce GTX 275 is pretty much half a GTX 295. Where the GTX 295 is a dual-GPU solution, the GTX 275 has only a single GPU on board, supporting 896MB of memory. That single core runs at the same clock speed as the cores in the 295.

The most striking thing (to me) about the GTX 275 is how similar it is to the GTX 285. The core shader and memory clocks are slightly slower than the 285, but only slightly. The core is around 2% slower; the memory about 10% slower.

The GTX 275 supports 896MB as opposed to 1GB on the 285, has a 448-bit bus (the GTX 285 has 512-bit) and has 28 render output units as opposed to 32 on the 285.

As you’d expect, there isn’t much performance difference between the two chips. According to tests run by Tom’s Hardware Guide, for example, the GTX 275 is about 6% slower than the 285 in 3D Mark Vantage.

I guess the GTX 275 is a testament to Nvidia’s modular design that allows it to put out chips with slight variations like this, but I do have to wonder if there really is a point in releasing a chip that's almost exactly like one already available, only slightly worse.

Head to head

As with any new chips released, there are plenty of benchmarks available online, including a full review of the ATI at our sister site Atomic MPC.

If you’re interested in seeing how the two new chips go head to head (and they’re expected to be around the same price), I’d recommend checking out AnandTech or FiringSquad.

The I-couldn’t-be-bothered-clicking-on-the-links takeaway is that the two chips are fairly evenly matched in most benchmarks, usually coming within a few FPS of each other (though there are a few strange outliers, such as in Call of Duty 4).

The results are somewhat dependant on the game – sometimes the GeForce came out a little ahead, sometimes the ATI. All in all, I’d say there’s not a lot of daylight between the two chips.

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solicitmyself Apr 4, 2009 5:38 AM	but it still can’t match the integrated SLI performance of the 4870 X2. it's integrated crossfire not sli (which is nvidia pairing)
solicitmyself Apr 4, 2009 5:39 AM	but it still can’t match the integrated SLI performance of the 4870 X2, it's integrated crossfire (sli is nvidia pairing)
macka71 Apr 4, 2009 9:25 AM	an error (typo) in the article: The chips – "Nvidia GeForce HD 4890" should read "Nvidia GeForce GTX 275" but everyone reading this would know that already.