Radeon HD 7870 is a graphics card that set high expectations, as, unlike Cape Verde, the Pitcairn GPU has a lot more power “under the hood”. Consequently, this mid-range model is closer to Tahiti-based ones, and seems like a very interesting buy for the users that wish to equip their PC with the latest piece of silicon, but at a reasonable price. Radeon HD 7870 has enough power to cope with all new titles in resolutions such as 1920x1080 at maximum detail levels, which is excellent news. Also interesting is the fact that a well-overclocked Radeon HD 7870 is able to compete against models such as GeForce GTX 580 and Radeon HD 6970 in resolutions up to full HD, which is yet another plus for AMD, as they’ve managed to create a pretty efficient GPU for its class.
Pitcairn belongs to the Southern Islands family, and is made in 28 nm as such. All technologies that go into Tahiti have been implemented in Pitcairn too, consequence of which is Pitcairn’s 2.8 billion transistors – an impressive number indeed. Owing to advanced lithography, its surface isn’t all that great, and neither is its power consumption, declared to a maximum of 175 W. Pitcairn isn’t a chip where a lot of compromises were made, so it has 1280 stream processors, 80 texture and 32 ROP units – fantastic values all around. With the fact that this GPU ticks at 1000 MHz, it’s clear why AMD has branded it as “sweet spot”. These models are all accompanied by a 256-bit bus, but also 2 GB of GDDR5 memory, which we still consider to be the optimal amount; you’ll hardly need more than this, unless you’re sporting a monitor above the full HD resolution or a multi-monitor system such as Eyefinity. As expected, ASUS and Sapphire provided us with their overclocked Radeon HD 7870, created to help you squeeze out the last bit of performance out of this chip, giving you maximum performance for the money invested. Let’s start off with ASUS, or more specifically, you’ve guessed it, their DirectCU II model.
ASUS Radeon HD 7870 TOP DirectCU II
ASUS graphics cards with DirectCU II cooling are about as surprising as the sun rising in the east these days, but what actually did surprise us was how unsatisfied we were with the DirectCU II version of HD 7850 – it proved to be too noisy and not as efficient as usual. ASUS was quick to get the message, though, so even if it’s the same solution this time around, changes were made to the most critical spots. There isn’t much to say about the packaging, as ASUS hasn’t been paying particular attention to the bundle for a while now, so you’re treated to the same bare-bone essentials as the last few times. As for the card itself, the cooler shield is still made of plastic, but this isn’t an issue whatsoever, as the cooler remains as visually attractive as always. If you still recall, we mentioned that Radeon HD 7850 DirectCU II had different fans, one of which was quiet, and the other one noisy. ASUS was quick to grasp the situation and opted for quiet and identical fans this time, which is a huge plus in our eyes. These 80 mm fans have proven to be very quiet, thanks to good design and large blades, but most importantly, their “hiss” is deep, so you won’t be too harassed by them even if you manually increase their speed. The aluminium cooling profile has remained largely the same, but the four heatpipes are thicker than they used to be, measuring some 8 mm in diameter. As this is DirectCU cooling we’re talking about, these nickel-plated heatpipes lie on the GPU surface directly, which increases cooling efficiency significantly.
Beneath the cooler, one is greeted by the PCB, which suffered its share of amendments as well compared to the referent solution. Firstly, the card has a Digi+ VRM power unit, a technology exclusive to ASUS. Besides, all elements belong to the Super Alloy Power series and are of utmost quality, and we also dig the fact that all six phases (the default design capabilities of the card) are put to good use. As the model name contains the TOP suffix, it shouldn’t come as a surprise that the GPU is overclocked from 1000 MHz to 1100 MHz, an increase of exactly 10% over the referent value. Furthermore, the memory has been slightly bumped up, from 4800 MHz to 5000 MHz, which may not be as visible in performance output, but is nice to see nevertheless. Of course, since the card has such a good power unit and excellent cooling, we didn’t hesitate to crank it up to “red” and see just how far we can get. We were stopped at 1230 MHz for the GPU and 5700 MHz for the memory, which is more than satisfying overall. These clocks required a voltage of 1.23 V, which kept the card fully stable, although the fan got a bit noisier (not enough to actually bother anyone, though). Speaking of connections, this card has two DVI outputs, as well as one DisplayPort 1.2 and HDMI 1.4a, which is in line with the referent design, so no ASUS intervention was needed in this aspect.
Sapphire Radeon HD 7870 OC
Sapphire’s engineers didn’t take long to present the more advanced model alongside the referent HD 7870 version; the former has a redesigned, tangibly better cooling, as well as clocks higher than stock ones, which is a trend we fancy a lot. The folks at Sapphire have decided to “wrap” their card in plastic, while the rough surface texture looks fantastic in combination with a matte black shield. The fans are larger than ASUS’, with a diameter of 90 mm – an advantage that always reflects on noise and temperature alike. Sapphire’s model seems to be more massive in general, owing to the somewhat larger cooling profile than on its ASUS counterpart. The profile in question is made of aluminium, intersected by four heatpipes with uneven diameters (two of them 8 mm, the other two 6 mm). The phenomenon of varying heatpipe diameters is definitely on the rise on Sapphire’s cards, with the thicker ones crossing the farther sections of the cooler, i.e. its edges. This likely helps increase efficiency. The base is also made of aluminium, but has a splendid finish and seems like a perfect match for a GPU with the surface of 212 mm. Furthermore, Sapphire has covered all memory chips with a passive cooler, admittedly no more than a thin aluminium frame, but certainly better than leaving the chips “naked”. This “frame” also cleverly covers the VRM chips. The power unit is simpler than ASUS’, with 5-phase voltage filtering, but this isn’t likely to be a problem for several reasons. All “thoroughbred” Southern Islands chips peak at between 1200 and 1280 MHz, regardless of whether they use the default or the “aftermarket” power unit. Of course, we’re talking about regular conditions, not liquid nitrogen-cooling or similar. Besides, it’s been proven that high-quality cooling is what matters most as far as overclocking is concerned (besides the actual GPU quality), and this is where Sapphire strikes gold. This company issued the overclocked model with frequencies lower than those on ASUS card, although the default GPU value of 1050 MHz still qualifies for the model to be called factory-overclocked. The memory has been sped up to an effective 5 GHz (1250 MHz actual clock).
Interestingly enough, the outputs are slightly different, with two mini-DisplayPorts, one HDMA 1.4a and one DVI, but having in mind the number of adapters Sapphire supplies with their cards, the choices are essentially the same. The rich bundle includes not only the basic niceties, but also the Sapphire Select Club membership card, a 1.8-metre long HDMI cable and several video adapters, proving once again that Sapphire is at the lead in terms of extra content lately.
After a good week or so spent with these models, we were able to reach several useful conclusions. At default clocks, ASUS’ model was slightly faster than Sapphire’s owing to its 50 MHz higher clock for the GPU. On the other hand, it also heated up more substantially, going up to 71 degrees Centigrade at times. Besides, the smaller, more aggressive fans made this model noticeably noisier. Take the latter statement with a grain of salt, as the card was still fairly quiet generally speaking, but it just couldn’t compare with the virtually silent Sapphire.
|Test Results||ASUS Radeon HD7870 DirectCU II||Sapphire Radeon HD 7870 Overclock Edition|
|1920x1080 0xAA 0xAF / 1920x1080 4xAA 16xAF||1100MHz / 1250MHz (Efectivly 5GHz)||1050MHz / 1250MHz (Efectivly 5GHz)|
|3DMark 11 (Extreme preset) GPU Score
||2.016 / 2.935||1.952 / 2.854|
|3DMark Vantage (high preset) GPU Score
||17.451 / 14.896||17.163 / 14.404|
|Unigine Heaven 2.5 (DX11, high, tesselation) [fps]
||69,8 / 55,6||69,1 / 55,1|
|Crysis 2 (DX11, Ultra, HR Textures) [fps]
||71,9 / 66,4||68,1 / 63,9|
|Crysis Warhead (DX10, Enthusiast) [fps]
||51,7 / 45,6||50,7 / 42,7|
|Metro 2033 (DX11, very high, tesselation) [fps]
||48,3 / 39,9||48,1 / 38,8|
|AvP DX11 (DX11, max) [fps]||77,8 / 47,7||76,9 / 48,2|
|F1 2010 (DX11, max) [fps]||69 / 62||68 / 61|
|Dirt 3 (DX11, Ultra) [fps]||78,7 / 73,4||76,1 / 71,8|
|Lost Planet 2, Test B (DX11, high) [fps]||59,7 / 49,5||59,3 / 49,2|
|Test configuration||Intel Core i5 760 @ 3,8GHz, 2 x 4GB AMD Memory 1600MHz DDR3, ASUS Maximuss III Extreme, WD 500GB, Windows 7 64bit Ultimate, Catalyst 12.3|
ASUS’ overclock potential also wasn’t as good as Sapphire’s, with the card reaching up to 1240 MHz. On the other hand, Sapphire peaked at 67 degrees, at lower fan RPM rates, owing primarily to the fan dimensions. Furthermore, they managed to raise the overclock limit for the GPU to 1280 MHz. Still, have in mind that, for everyday conditions, 1200 MHz is quite sufficient for both models. Finally, it should be stated that both Sapphire and ASUS have provided very worthy competitors, with the latter being somewhat warmer, but also slightly faster at stock speeds, while you’ll have trouble actually detecting noise coming from either card. Therefore, since both cards are only available in limited supply at the moment, we strongly suggest you wait a bit, see how the situation develops with prices and availability, and make your decision based on that.