ATI’s Radeon X1650 XT graphics card

Those numbers may be the recipe for success for the Radeon X1650 XT, making it a worthy rival of the GeForce 7600 GT at around $149. If so, this product arrives not a second too soon. It seems like ATI hasn’t had a credible offering in this segment of the market since hooded flannel shirts were all the rage. Can the Radeon X1650 XT break the red team’s mid-range curse? Let’s have a look.

Meet the wild child
The Radeon X1650 XT’s unassuming appearance conceals its true personality. Under that pedestrian single-slot cooler lies a wildly transgressive graphics card, driven by a GPU that refuses to honor the boundaries of class or convention. The X1650 XT is part of the Radeon X1600 series, yet its graphics processor is not the RV530 silicon that has traditionally powered cards in that product line. The intrigue gets even deeper when you examine this mysterious GPU, code-named RV560. Truth be told, this is actually the same graphics chip behind the Radeon X1950 Pro that we reviewed a couple of weeks ago, the R570. For the X1650 XT, though, ATI has disabled portions of the chip and assigned it a new code name. If I recall correctly, this is the first time ATI has fabricated two code names for the same piece of silicon. So basically, ATI has chucked the conventions for both video card names and GPU code names in recent weeks, and the Radeon X1650 XT is the result.

Not that there’s anything wrong with that.

In fact, the X1650 XT benefits from its upper-middle-class heritage. Its RV570 GPU (sorry, but I’m not calling it RV560) has had a portion of its on-chip resources deactivated, either because of faults in some parts of the chip or simply for the sake of product segmentation. This hobbled GPU can still take on the GeForce 7600 GT with its one good arm, though, thanks to 24 working pixel shaders, eight vertex shaders, and eight texture units/render back-ends. These rendering bits and pieces run at a GPU core clock of 575MHz. To keep card costs down, the Radeon X1650 XT has only a 128-bit path to memory (like the GeForce 7600 GT) and not 256 bits (like its big brother, the X1950 Pro.) The X1650 XT’s 256MB of GDDR3 RAM runs at 675MHz.

The X1650 XT’s cluster of ports befits a brand-new graphics card. The two dual-link DVI ports come with full support for HDCP, so they can participate in the copy-protection schemes used by the latest high-def displays.

If you’re driving a big display at high res with an X1650 XT, you may want to give it some help in the form of additional X1650 XT cards that run alongside it. That’s a distinct possibility thanks to the pair of internal CrossFire connectors on the top edge of the card. We’ve tested the X1650 XT in a dual-card CrossFire config, and ATI has confirmed for us that they plan to enable support for more than two cards in CrossFire using staggered connectors at some point in the future, although we don’t know much more than that.

That’s pretty much it for the Radeon X1650 XT’s basic specifications. Of course, it’s based on very familiar Radeon X1000-series GPU technology, with features and image quality that match everything up to the Radeon X1950 XTX. ATI says to expect cards at online retailers the week of November 13. The big remaining question is performance.

Test notes
We did run into a few snags in our testing, although none of them affected the Radeon X1650 XT. Most notably, when we tried to run a pair of GeForce 7600 GT cards in SLI, we encountered some odd image artifacts that we couldn’t make go away. The image artifacts didn’t appear to affect performance, so we’ve included results for the GeForce 7600 GT in SLI. If we find a resolution for the problem and performance changes, we’ll update the scores in this article.

Also, the 3DMark06 test results for the Radeon X1950 XTX CrossFire system were obtained using an Asus P5W DH motherboard, for reasons explained here. Otherwise, we used the test systems as described below.

Our testing methods
As ever, we did our best to deliver clean benchmark numbers. Tests were run at least three times, and the results were averaged.

Our test systems were configured like so:

Thanks to Corsair for providing us with memory for our testing. Their quality, service, and support are easily superior to no-name DIMMs.

Our test systems were powered by OCZ GameXStream 700W power supply units. Thanks to OCZ for providing these units for our use in testing.

Unless otherwise specified, image quality settings for the graphics cards were left at the control panel defaults.

The test systems’ Windows desktops were set at 1280×960 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

We used the following versions of our test applications:

• Quake 4 1.3 with trdm1 netdemo
• The Elder Scrolls IV: Oblivion 1.1
• Ghost Recon Advanced Warfighter 1.21
• F.E.A.R. 1.07
• Half-Life 2: Episode One with trdem1 demo
• FutureMark 3DMark06 Build 1.02
• FRAPS 2.7.2

The tests and methods we employ are generally publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Pixel-filling power
I’m inclined to chuck our fill rate table out of the window soon, because it’s becoming less relevant as programmable pixel shaders become more prevalent. Still, we’ll have a quick look at it here, since it helps illustrate what the Radeon X1650 XT has over the rest of the Radeon X1600 lineup.

Although it has nearly the exact same amount of memory bandwidth as its little brother, the Radeon X1650 Pro, the X1650 XT can paint nearly twice as many pixels with its GPU each second. In fact, the X1650 XT’s pixel fill rate surpasses that of the GeForce 7600 GT. The GeForce, however, has more peak texturing capacity.

All of this tech talk doesn’t mean much if the cards can’t deliver on their theoretical promise, however. This quick synthetic fill rate test checks to see how close they can get.

The X1650 XT can’t quite match the GeForce 7600 GT in these tests, but it does get very close to its own peak theoretical throughput when applying multiple textures. For its part, the BFG Tech 7600 GT OC card slightly outperforms the theoretical peak numbers we have in the table above because it’s running at higher-than-stock clock speeds. These things are merely academic at the end of the day, though, so let’s move on to real games.

Quake 4
In order to make sure we pushed the video cards as hard as possible, we enabled Quake 4’s multiprocessor support before testing.

There are an awful lot of LCD displays out there these days with 1280×1024 resolution. Although it’s tempting to try given the numbers, I don’t think I’d attempt to play through Quake 4 on a Radeon X1650 XT at these quality settings and that resolution. Based on my experience, frame rates can get rather choppy. Dropping back to 2X AA seems to yield more consistently acceptable performance, although that’s a compromise GeForce 7600 GT owners likely won’t have to make in this game.

The Radeon X1650 XT CrossFire rig does quite well up to 1600×1200 resolution, but it appears to hit a wall at 2048×1536. The GeForce 7600 GT in SLI handles this crazy-high res more gracefully.

F.E.A.R.
We’ve used FRAPS to play through a sequence in F.E.A.R. in the past, but this time around, we’re using the game’s built-in “test settings” benchmark for a quick, repeatable comparison.

Ok, so F.E.A.R. at its max quality settings is admittedly a bit much for any single graphics card in this price range. The X1650 XT does match up well to the GeForce 7600 GT in single-card performance, but it suffers from the same odd issues that other Radeons do in CrossFire mode in this game.

Half-Life 2: Episode One
The Source game engine uses an integer data format for its high-dynamic-range rendering, which allows all of these cards to combine HDR rendering with 4X antialiasing.

This is a good-looking game, but it doesn’t have the most complex lighting, so it runs reasonably well on a mid-range graphics card. Here, the X1650 XT has a bit of an edge over the 7600 GT. I played this game some with a single Radeon X1650 XT, and it runs smoothly enough at 1280×1024 with 4X AA and HDR. Using those settings at 1600×1200 is pushing it, though.

The Elder Scrolls IV: Oblivion
We tested Oblivion by manually playing through a specific point in the game five times while recording frame rates using the FRAPS utility. Each gameplay sequence lasted 60 seconds. This method has the advantage of simulating real gameplay quite closely, but it comes at the expense of precise repeatability. We believe five sample sessions are sufficient to get reasonably consistent and trustworthy results. In addition to average frame rates, we’ve included the low frames rates, because those tend to reflect the user experience in performance-critical situations. In order to diminish the effect of outliers, we’ve reported the median of the five low frame rates we encountered.

We set Oblivion’s graphical quality settings to “Ultra High.” The screen resolution was set to 1600×1200 resolution, with HDR lighting enabled. 16X anisotropic filtering was forced on via the cards’ driver control panels.

The Radeon X1650 XT just barely edges out the GeForce 7600 GT in Oblivion. The performance numbers are awfully close, but you will appreciate the Radeon’s superior texture filtering in this game.

This is another instance where our chosen comparative test resolution is a bit out of a single X1650’s league. I did try playing some Oblivion on the Radeon X1650 XT with these same quality settings at 1280×1024, and it ran quite well. I was impressed.

Ghost Recon Advanced Warfighter
We tested GRAW with FRAPS, as well. We cranked up all of the quality settings for this game, with the exception of antialiasing. However, GRAW doesn’t allow cards with 256MB of memory to run with its highest texture quality setting, so those cards were all running at the game’s “Medium” texture quality.

This one is really too close to call. Although the GeForce 7600 GT’s average frame rates in single and dual-card configurations is higher, its median low frame rates are very similar to the Radeon X1650 XT’s.

3DMark06

The 3DMark scores simply serve to confirm what we’ve already seen: the Radeon X1650 XT and GeForce 7600 GT are extremely closely matched in performance.

The 7600 GT takes two out of 3DMark’s three synthetic shader tests, but the X1650’s eight vertex shaders give it the edge in the complex vertex test.

Power consumption
We measured total system power consumption at the wall socket using an Extech power analyzer model 380803. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement. We tested all of the video cards using the Asus P5N32-SLI SE Deluxe motherboard, save for the CrossFire system, which required a different chipset. For that system, we used an Intel D975XBX motherboard.

The idle measurements were taken at the Windows desktop. The cards were tested under load running Oblivion using the game’s Ultra Quality setting at 1600×1200 resolution with 16X anisotropic filtering.

The performance race between the Radeon X1650 XT and the GeForce 7600 GT is practically too close to call, but here we see some real differences. The X1650 XT draws about 10W more than the 7600 GT at idle and about 30W more under load. That’s really not surprising considering that the Nvidia G73 GPU is about 125 mm², while the RV570 is 230 mm². Oddly enough, the X1650 XT seems to draw a little more power than the higher end Radeon X1950 Pro based on the same GPU.

Noise levels and cooling
We measured noise levels on our test systems, sitting on an open test bench, using an Extech model 407727 digital sound level meter. The meter was mounted on a tripod approximately 14″ from the test system at a height even with the top of the video card. The meter was aimed at the very center of the test systems’ motherboards, so that no airflow from the CPU or video card coolers passed directly over the meter’s microphone. We used the OSHA-standard weighting and speed for these measurements.

You can think of these noise level measurements much like our system power consumption tests, because the entire systems’ noise levels were measured, including CPU and chipset fans. We had temperature-based fan speed controls enabled on the motherboard, just as we would in a working system. We think that’s a fair method of measuring, since (to give one example) running a pair of cards in SLI may cause the motherboard’s coolers to work harder. The motherboard we used for all single-card and SLI configurations was the Asus P5N32-SLI SE Deluxe, which on our open test bench required an auxiliary chipset cooler. The Asus P5W DH Deluxe motherboard we used for CrossFire testing didn’t require a chipset cooler, so those systems were inherently a little bit quieter. In all cases, we used a Zalman CNPS9500 LED to cool the CPU.

Of course, noise levels will vary greatly in the real world along with the acoustic properties of the PC enclosure used, whether the enclosure provides adequate cooling to avoid a card’s highest fan speeds, placement of the enclosure in the room, and a whole range of other variables. These results should give a reasonably good picture of comparative fan noise, though.

We measured the coolers at idle on the Windows desktop and under load while playing back our Quake 4 nettimedemo. The cards were given plenty of opportunity to heat up while playing back the demo multiple times. Still, in some cases, the coolers did not ramp up to their very highest speeds under load. The Radeon X1800 GTO and Radeon X1900 cards, for instance, could have been louder had they needed to crank up their blowers to top speed. Fortunately, that wasn’t necessary in this case, even after running a game for an extended period of time.

You’ll see two sets of numbers for the GeForce 7950 GT below, one for the XFX cards with their passive cooling and another for the BFG Tech cards, which use the stock Nvidia active cooler. I measured them both for an obvious reason: they were going to produce very different results.

As we’ve noted before, small coolers tend to be noisy, and the X1650 XT can’t entirely escape that fact. This card really isn’t a terrible offender overall. It’s a little louder at idle than most, but not horrible. While running a game, the X1650 XT’s cooler doesn’t crank up to the kind of high-pitched whine you get from the GeForce 7600 GT, thank goodness. The difference shows on our decibel meter.

CrossFire, on the other hand, is another story—especially under load. I’m not sure if there was some kind of odd harmonic effect between the two X1650 cards’ coolers or what. Readings on the decibel meter seemed to cycle up and down through a much broader range than we’ve seen from other coolers. I tried to pick a reasonable center of that range to include in our results, and it turned out to be louder than anything else we’ve recorded. I wouldn’t worry too much about that, though. Subjectively, the X1650 XT isn’t an especially loud card.

Overclocking
I had some trouble using ATI’s auto-overclocking utility to find the optimal clock speed in our Radeon X1950 Pro review, but I ran into no such issues with the X1650 XT. The utility settled on 621MHz core and 763MHz memory clocks for both single-card and CrossFire configs—pretty much maxing out the peak values for the manual sliders in the control panel—and both were stable at those speeds.

Unfortunately, overclocking this thing to the apparent max in ATI’s control panel doesn’t get you much additional performance. The headroom does seem to be there, though, to take it up quite a ways.

Conclusions
The Radeon X1650 XT performs almost exactly on par with the GeForce 7600 GT overall. At long last, it establishes a performance balance between ATI’s Radeon X1000-series products and Nvidia’s GeForce 7 series products at $149. This same performance balance has existed for a while at other price points, and things are tighter than ever after the fall round of graphics card refreshes.

In fact, I’m a little surprised to see ATI simply meeting Nvidia with a product that offers nearly equivalent performance to the GeForce 7600 GT. Typically, you’d expect some one-upsmanship to kick in here. After all, it’s not like the GeForce 7600 GT wasn’t a well-defined target—it’s been selling since March. Had ATI pushed the GPU or memory clocks a little further, they could have grabbed the decisive performance lead.

The respective strengths of these two competing graphics technologies remain more or less the same at $149 as elsewhere. GeForce 7 chips tend to be smaller and more power efficient, while the Radeon X1000 series sports a handful of additional features that can lead to higher image quality. I think those picky image quality differences tend to matter more in high-end graphics cards where advanced texture filtering and antialiasing modes will get more use. In this case, I wouldn’t give the Radeon X1650 XT a decisive edge over the GeForce 7600 GT on that basis. ATI may have the advantage, though, simply because the Radeon X1650 XT is a newer product with dual-link DVI outputs and support for HDCP.

The question of dual-card capability is an intriguing one. No CrossFire config we’ve tested, including the X1650 XT, seems to handle F.E.A.R. well. Overall, Nvidia’s SLI seems to be the more mature dual-GPU solution. On the other hand, we can’t really recommend SLI for the GeForce 7600 GT given the “green fringing” problem we’ve encountered. We haven’t seen a fix for this problem in the two months since we first reported it. I suspect not many folks are running GeForce 7600 GT cards in SLI, or we’d have a fix by now. That’s a shame, because whether you’re talking ATI or Nvidia, running a pair of $149 graphics cards in a dual-GPU config actually looks like a pretty decent value for the money.

Speaking of value, the X1650 XT’s value proposition is a tricky subject. If you happen to have a monitor whose optimal resolution is 1280×1024 or (shudder) lower, you really don’t need more graphics card than the Radeon X1650 XT in order to run today’s games at some fairly high quality settings. Dropping $149 for one of these cards will give you a monstrous improvement over the awful built-in graphics in most cheaper PCs, and you may not need to spend any more.

Then again, there are much better graphics cards to be had for just 50 bucks more, including the Radeon X1950 Pro and the GeForce 7900 GS, both of which feature 256-bit memory interfaces for roughly twice the bandwidth of the X1650 XT. That means they’ll run games with more antialiasing, higher quality settings, and better texture filtering without slowing down. The additional $50 will probably be money well spent for all but the most casual of gamers, especially over the long run as newer, more demanding games arrive.