Although it’s been more than a month since we presented the first Radeon HD 7950, everything about it was pretty rushed due to a very tight deadline; this time around, though, we’ve had the chance to hang out with several different models, making for a proper way to get acquainted with the new chip. As we’ve already mentioned on a few occasions, the latter is AMD’s newest chip in the upper class, codenamed Tahiti, and also the first chip to have been manufactured in the 28 nm production process. The story began with Radeon HD 7970, but shortly unravelled further with the presentation of its weaker brother, HD 7950, which is the more cost-conscious version.
These cards are somewhat weakened due to their using partially dysfunctional GPUs. This is a tradition set long ago by both NVIDIA and AMD, as the chips usually have most of the fully-fledged version’s performance, with only a small bit of the chip “cut off” from the fully capable remainder of it, which makes the entire card a lot cheaper in retail and keeps the yield high. Exceptions have been made on a few occasions, as was the case with Radeon HD 5830, which didn’t fare all that well back in the day as the price was too high and the performance too hampered. However, this won’t be happening with Radeon HD 7950, as it’s so close to its older brother that it’s practically breathing behind its neck, at least on paper. A difference of 256 stream processors and 16 texture units combined with slightly reduced clocks is definitely nothing worthy of resentment, while 100€ more in the buyer’s pocket is hugely important in this day and age. We got three models for testing, namely by Sapphire, ASUS and MSI.
The largish packaging contains Sapphire’s model, which offers quite a bit in its accompanying bundle to attract potential customers, and breaks the monotony we’ve witnessed lately with many manufacturers. The box contains not only the card, but also that substantial little extra. Of course, a good bundle means nothing when the product is bad, but in an era when all manufacturers tend to offer an excellent cooling solution, good overclock abilities and high-quality hardware in general, it’s bits and bobs like this that can make or break a buyer’s decision. In accordance with this principle, Sapphire accompanies its model with a gold membership card in their privilege club, which enables the user to receive a game coupon every now and then, as well as high-priority customer support. As for physical goods, there’s a 1.8-metre HDMI cable, as well as loads of other standard features, such as connectors, converters, documentation and hardware.
The card looks recognisable enough for Sapphire, particularly due to its peculiar cooler design. Although the cooling profile is always a bit different between various models, it manages to keep some basic characteristics that never change. The combination of black shielding that doesn’t cover the card entirely and the balance of glossy and matte plastic with several stickers on top has been Sapphire’s signature style for a while now. Two large fans with densely packed and long blades look promising in terms of noise levels. Their diameter isn’t particularly impressive at 90 mm, but they do enable very good airflow and good performance. Aluminium fins have been used for the cooling profile, with the obligatory addition of heatpipes across them. There is a total of five heatpipes, two of which are thicker (8 mm), while the other three are thinner by one millimetre. They spread the heat efficiently and evenly from the cooler base to the rest of the cooling body, where the heat is then taken up by fans. Unfortunately, as this isn’t the Vapor-X cooling system, the heatpipes don’t like directly on the cooler surface, instead going through the base, which makes the heat change environment several times, resulting in a lower efficiency level compared to Vapor-X and DirectCU solutions.
The GPU contained underneath is the already described version of the Tahiti chip, weakened in comparison to the one seen on HD 7970. It’s surrounded by twelve GDDR5 memory chips, forming a 384-bus. Their frequency is initially set to respect the referent values of 1250 MHz, or 5 GHz effectively, which gives a high memory bandwidth of 240 GB/s. Unlike the memory, the GPU is working at a higher default clock of 900 MHz, enabled due to custom cooling. The fan remained very quiet even when set to as high up as 70%, while the temperatures remained extremely low at all times. These are excellent conditions for a good overclock margin. As the card didn’t have the capability of software voltage regulation, we had to stick to initial values. Interestingly, the GPU reached 1 GHz, while the memory went along to an incredible 6.3 GHz. Temperature was kept below 65 degrees at all times, even with these settings
As far as video outputs go, the configuration is the same as in the referent HD 7970 and 7950: two mini-DisplayPorts, an HDMI and a DVI, which is enough for anyone’s needs. Two CrossFireX connectors can be found along the upper edge of the PCB, as well as a microswitch used to select the active BIOS. Two are at the user’s disposal, one of which is modifiable, while the other one is protected and serves only as backup in case something goes wrong. All in all, a very good card across all its aspects.
Like all other high-end models with DirectCU II cooling, this card is huge. The well-known cooling system is both awe-inspiring and worrying, as it occupies two adjacent slots. This may cause troubles to users with cramped enclosures or numerous components on the inside, such as CrossFireX systems, audio cards or similar. However, other than its sheer physical size, this cooling system is remarkable, and its aesthetic side isn’t to be easily dismissed either. The three-slot cooler consists of an aluminium cooling profile and five 8 mm-thick heatpipes. The cooling body is massive, consisting of densely packed fins. As the technology in question is DirectCU II, the heatpipes lie directly on the GPU, increasing heat transfer efficiency and spreading the strain across the entire cooler.
The fans have a diameter of 100 mm, which keeps them quiet in action. We were sorry to see that the power unit cooling has been left out, and the same goes for the memory chips, which are “left to themselves”. Furthermore, ASUS seems determined at refusing to mount backplates on Radeon cards, so unlike NVIDIA-based solutions, these ones seem a lot less secure, as the cooler is kept in place only by four thin surface screws. The specs of the card are practically identical to the ones on Sapphire’s model. However, ASUS achieved better results at overclocking, as software voltage regulation for the GPU was enabled for this card. With the fantastic cooling system, preventing the GPU from going over 58 degrees at any point, it was clear that our chances of overtaking Sapphire in overclock were big. And so it was – we were able to reach 1100 MHz for the Tahiti chip with a voltage 1.25 V, while the memory wasn’t as much in the mood. The default 5 GHz increased to 6.2 GHz, which is almost as good as Sapphire’s model, but the GPU is what truly matters, as the memory bandwidth is excellent to begin with, and more than sufficient for the needs of this GPU.
Finally, the connectors – ASUS’ Radeon HD 7950 has two CrossFireX connectors, while communication with the motherboard is done via PCI-Express 3.0. As for video outputs, there are two mini-DisplayPorts (1.2 revision), one DVI and one HDMI 1.4a. As one can see, ASUS has followed AMD’s referent specifications to the letter.
Just like ASUS, MSI also has their own brand of cooling, named TwinFrozr, which has advanced to its third generation. We were first able to see it back in the era of GTX 580, and MSI has since placed it on all of its factory-overclocked models. The similarities with ASUS don’t end here – the bundle is just as modest, and we’re sorry to see manufacturers straying away from the path set by Sapphire. Still, once you’ve got hold of the card which doesn’t have a single piece of plastic on it (being made entirely out of metal), you’re bound to be impressed.
The MSI product is dominated by the cooling system (surprise surprise), and the aluminium shield covers most of the card, revealing little but the side details. Like all other models in this roundup, MSI is also using a dual-fan system. The fans have a diameter of 90 mm, but with fairly short blades, specially curved and thinned at the ends in order to increase airflow, reduce noise and keep dust at bay. The latter two may be marketing claims, but we believe that airflow has in fact been improved, as cooling really is more efficient than ever. The rest of the profile is comprised of aluminium fins traversed by six nickel heatpipes. They stretch through the cooling body and spread heat evenly across its entire surface. Although the heatpipes don’t like on the GPU directly, the base has a very good finish, so the latter isn’t too much of a drawback. Still, we’d like to see MSI following in the steps of other manufacturers, which is likely to happen with models with a higher TDP. As far as temperature is concerned, the maximum of 54 degrees with a very low noise level can be deemed remarkable. The only thing we have to reproach is that, just like DirectCU II cooling, there’s no backplate. That leaves Sapphire’s model as the only one that doesn’t have tilting problems, while the coolers seen on the other two definitely require more than the four screws they have to keep them tightly in place.
Like all other models, this card also uses the referent PCB, with a higher-quality power unit, as HD 7950 TwinFrozr III has “Military Class II” components implemented. Video outputs are identical to the other cards in this review, which means one DVI and one HDMI 1.4a, as well as two mini-DisplayPorts. Again, the upper edge has two CrossFireX connectors, as well as a BIOS switch. Powering this card requires two 6-pin molex connectors in place, which is another characteristic common to all Radeons HD 7950.
As for clocks, MSI too has factory-overclocked their representative, setting the bar 20 MHz lower than Sapphire and ASUS. It’s interesting that none of the manufacturers has bothered to raise the default memory frequency from the default 1250 MHz, which is strange when the fact that they all managed to climb over 6 GHz is taken into account. We got to 1100 MHz for the GPU with MSI’s youngling, which is the limit of the Catalyst Control Centre rather than the GPU itself, but the voltage required was lower than in ASUS’ case at 1.2 V.
The memory easily attained 1575 MHz, or 6.3 GHz effectively. All this was done with the fan set to 50% of its maximum RPM rate, which creates little noise, while the temperature was constantly below 60 degrees.
All these values are no less than fantastic, especially since the card packs a dual-slot, and not a tri-slot cooler (by the way, look at how we’re referring to dual-slot coolers as thinner variants nowadays, whereas a few years ago they were considered bulky). Of course, overclock performance always depends on the sample you have in hand, so the values we were able to achieve are by no means guaranteed or any sort of general rule, just a guideline.
CPU: Intel Core i5 760 @ 3,8GHz
RAM: 2 x 4GB AMD Memory 1600MHz DDR3
MoBo: ASUS Maximuss III Extreme
Storage: WD 500GB
Display: LG W2363D
Dual PSU: Cooler Master UCP 900W
OS: Windows 7 64bit Ultimate
Driver: Catalyst December Tahiti Driver
Sapphire Radeon HD7950 3GB OC
|ASUS Radeon HD7950 3GB DirectCU II||MSI Radeon HD7950 3GBTwinFrozr III|
|GPU Clock [MHz]||900||900||880|
|No. of Stream Processors||1792||1792||1792|
|ROP / Texture Units||32 / 112||32 / 112||32 / 112|
|Memory type / capaticy / bus width||GDDR5 / 3 GB / 384-bit||GDDR5 / 3 GB / 384-bit||GDDR5 / 3 GB / 384-bit|
|Memory clock / effective clock [MHz]||1.250 / 5.000||1.250 / 5.000||1.250 / 5.000|
|Sapphire Radeon HD7950 3GB OC||ASUS Radeon HD7950 3GB DirectCU II||MSI Radeon HD7950 3GBTwinFrozr III|
|GPU / MEM (efectively)||900MHz / 1.250MHz (5GHz)||900MHz / 1.250MHz (5GHz)||880MHz / 1.250MHz (5GHz)|
|1920x1080 4xAA 16xAF / 1920x1080 0xAA 0xAF|
|3DMark 11 (Extreme preset) GPU Score||2.521 / 3.777||2.501 / 3.779||2.488 / 3.719|
|3DMark Vantage (high preset) GPU Score||17.873 / 20.831||17.864 / 20.826||17.866 / 20.796|
|Unigine Heaven 2.5 (DX11, high, tesselation) [fps]||53,3 / 65,3||53,6 / 64,7||52,9 / 64,5|
|Crysis 2 (DX11, Ultra, HR Textures) [fps]||55,3 / 58,5||56,1 / 58,4||55,8 / 58|
|Crysis Warhead (DX10, Enthusiast) [fps]||50,2 / 56,7||50,5 / 56,2||50,3 / 55,9|
|Metro 2033 (DX11, very high, tesselation) [fps]||40,2 / 54,3||40,8 / 54,2||39,9 / 54,3|
|AvP DX11 (DX11, max) [fps]||55,3 / 90,1||55,6 / 89,9||55,2 / 89,1|
|F1 2010 (DX11, max) [fps]||69 / 73||68 / 73||69 / 72|
|Dirt 3 (DX11, Ultra) [fps]||70,1 / 78,4||71,9 / 78,5||69,6 / 77,7|
|Lost Planet 2, Test B (DX11, high) [fps]||55,2 / 65,4||55,3 / 65,9||54,3 / 64,3|
So, which card to opt for, a fatter or a slimmer one? The choice will have to depend on your affinities, as all three cards are very good. Sapphire has an excellent bundle and much more reasonable dimensions, but it’s also a bit warmer and less overclock-friendly than its other two counterparts.
On the other hand, ASUS is offering a bulky model that’s great all over, but won’t fit into any enclosure, and even if it does, it’s questionable whether you want to block the two adjacent slots.
Finally, MSI provides splendid cooling performance with all the advantages of a dual-slot cooler. The latter model also has the highest overclock margin with the lowest voltage. It’s clear that TwinFrozr III is one of the best cooling solutions on the market, and we’re surprised to see that MSI hasn’t increased the overclock range for its own model, as it was ultimately limited by the CCC only – who knows how much further it would’ve gone with the GPU value.