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Galaxy GeForce 7900 GT 256MB PCI-E Review |
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Written by Mavke
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Friday, 07 July 2006 |
PureOverclock brings us a review on the Galaxy GeForce 7900 GT 256MB PCIe graphics card. Recently we looked at the Radeon X1900 GT and weren't overly impressed. It is priced to compete against NVIDIA's GeFOrce 7900 GT and on paper looked as if it would be a close battle, but one worrying point within the specification seemed to be the 12 texture units. Sadly this did turn out to be the major bottleneck responsible for its poor performance. The Radeon X1900 GT failed to make an impact in our test suite. We'd urge anyone considering the Radeon X1900 GT to avoid it like an old person with a cold. It is just no match for NVIDIA's GeForce 7900 GT.
 Galaxy GeForce 7900 GT 256MB PCI-E Review
There is a reason ATI could not offer a card to compete to the GeForce 7900 GT and it should be explained. The core used for the Radeon X1900 series is R580. It is a 48 pixel shader, 16 texture unit chip, and is built using quads. Each of these quads consist of 12 of those pixel shaders and 4 of those textures units, meaning there is four quads in R580. When cores are graded or binned but found they cannot run at the core frequency needed for say, the XTX cards, or found to have a faulty quad, they will be used in other lower end cards. This has been a logic that ATI has been applying for quite some time.
For example, any core that fails to run at XTX speeds but can run at XT speeds will end up being used to build a Radeon X1900 XT card. Obviously when binning for an XTX card the core will have to be capable of much higher than 650MHz, probably 680MHz before being deemed acceptable, and the same would be true of the XT cards. So, the Radeon X1900 XT allows ATI to make use of many R580 cores that would otherwise end up in big pit under the desert, but when a full quad is defunct, ATI can disable it completely, creating a 36 pixel shader, and that is exactly what you'll find in the Radeon X1900 GT.
I should point out at this stage that this is common practice in this industry. Just to illustrate, any NVIDIA G71 cores that cannot manage 700MHz but can handle 450MHz will end up as a GeForce 7900 GT. I should also note that demand for the cheaper products usually outstrips the ratio of failed cores, so though these under achieving cores will be out there in the retail channel, most of the time cores that would have been suitable for the GeForce 7900 GTX will end up in GeForce 7900 GT's. So this brings us to our topic of today, which just so happen to be a GeForce 7900 GT
The GeForce 7900 GT is built using G71, the same chip as found in the GeForce 7900 GTX. The difference in speed between the the two is solely down to core and memory clock speeds. Because of the simple design borrowed from G70 and the die shrink from 110nm to 90nm, the G71 is small, cool running and power efficient, the same cannot be said for ATI's R580 chip. Galaxy's card uses NVIDIA's reference design, so the layout and cooler should be familiar to you already. The cooler is tiny and light weight and shows with an impressive statement just how cool running and power efficient G71 really is.
The memory chips found on Galaxy's GeForce 7900 GT are Sumsung 1.4ns, theoretically capable of 1400MHz, so there appears to be some room for overclocking. The GeForce 7900 GTX comes with 1.1ns memory, so we'll have to see if this GeForce 7900 GT can match the 1600MHz found on those cards. The default speeds for the Galaxy GeForce 7900 GT are 450MHz on the core and 1320MHz on the memory. Normally I wouldn't be so enthusiastic when it comes to overclocking performance, but the GeForce 7900 GT is simply an underclocked GTX, so if you can match it's clocks you'll get massive performance boosts.
Because of this, overclocking performance becomes a major reason for owning a GeForce 7900 GT. At stock it already beats its competition, so when we delve into overclocking it's all about getting GTX like performance for a lot less money. The memory really did reach 1800MHz. The core reached a reasonable 578MHz. It's interesting to note that the clocks reached are going to give it a huge boost not dissimilar to the GeForce 7900 GTX which at stock is 650/1600MHz. You can see that though the core is lower, the memory is much higher, so you never know, it may even outperform stock GeForce 7900 GTX's
The GeForce 7900 GT holds it's own in the sub £200 segment and Galaxy's offering has shown me why. The new Radeon X1900 GT is nothing short of poor by comparison, and ATI's only hope lies with the now aging Radeon X1800 XT. At stock the GeForce 7900 GT is in my opinion on par with the Radeon X1800 XT. It offers a little more performance. When you take into consideration the massive performance gains offered by overclocking the GeForce 7900 GT it stands above and beyond all the rest as a truly outstanding product. There are only two issues that spoil the show for Galaxy and that's noise and build quality.
Galaxy were not named as one of the manufacturers with GeForce 7900 GT build quality problems, but I'd still urge caution. Unless you are willing to take the risk I'd stay away from voltage modding and not push things too hard, at least not until these issues are officially resolved by NVIDIA. Noise too is a bit over-the-top on this card and it does put a damper on what is an otherwise brilliant showing from Galaxy. If Galaxy could offer a third party cooler along with fully implementing the NVIDIA fan controller it would put this card into a league of it's own.
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