Review: The first card with 2GB of GDDR5
An important victory, we must say, and no, we’re not talking about the Beijing Olympic Games, but rather the heavyweight graphics category. Radeon HD 4870 X2 is currently the fastest graphics card on the planet.
The picture below shows a Sapphire Radeon HD 4870 X2 card, packing two powerful RV770 graphics processors running in Crossfire mode on one PCB. That’s why “X2” found its place in the name of the card, and note that this is a multi-GPU card. The product we have in front of us is called R700, it runs great, and the results speak for themselves. Geforce GTX 280 is finally dethroned, and Nvidia definitely has to do something about it, as we’re sure they will.
Radeon HD 4870 X2 is not the only card in AMD’s sleeve. RV770 obviously turned out better than many hoped, so ATI made another dual GPU card based on it. The named it HD 4850 X2, which means it’s a slower version of the HD 4870 X2. Apart from these two new dual GPU cards, HD 4870 with 1GB of GDDR5 was also announced.
You should know that HD 4870 X2 is the first card with 2GB of GDDR5 memory. The slower HD 3870 X2 also has 2GB of memory, but it’s a cheaper GDDR3 one. It’s important to note that dual chip cards don’t feature a shared frame buffer, meaning that a 1GB card actually features 512MB of memory per chip. In our HD 4870 X2 scenario, each RV770 core has 1GB of GDDR5 at its disposal.
Radeon HD 4800 cards are based on the same RV770 core built in 55nm, and it features an impressive number of 965 million transistors. Each card from the HD 4800 series comes with 800 shaders (HD 3800 has 320), 40 texture units (HD 3800 has 16) and 16 ROP units and DirectX 10.1 support, but cards run at different speeds.
Radeon HD 4870 X2 runs at 750 MHz, just like HD 4878. Of course, HD 4870 X2 is exactly that – two HD 4870s on one PCB, so this card will feature everything that HD 4870 brings – times two. One of the pros we found in this dual chip card is that it consumes less energy than two HD 4870s in Crossfire mode. Maximum consumption in Crossfire mode will hit 320W, whereas one HD 4870 X2 will consume up to 286W. The card is powered through one 6-pin and one 8-pin power connector located in the upper right corner of the card, just above the fan.
ATI kept the cooler from HD 3870 X2 card, only now both cooler blocks are made of copper, unlike HD 3870 X2 which featured only one. The fan is the same one you’ll find on a single GPU HD 4870 cards.
Opposite to the power connectors, you’ll find a Crossfire connector which will enable quad Crossfire, provided that you have another HD 4870 X2 card.
Below you’ll find a nice photo that shows all the cooler’s layers, all the way to the core. The photo shows two large and heavy copper blocks with a heatsink that doesn’t feature heapipes, but it has a lot of tall fins through which the air flows. Hynix memory is in contact with the cooler, whereas on the back it touches the metal heatsink.
The card is dual slot, so hot air will be blown out of the case. It’s important to know that appropriate case cooling is a must, as the air coming out of the card is so hot that we couldn’t expose our skin to it longer than 10 seconds. However, Nvidia’s dual chip card doesn’t fare better in this respect, either.
HD 4870 X2s fan is sometimes silent and sometimes loud, depending on the temperature, of course. During operation, temperatures hit up to 89 degrees Celsius.
Radeon HD 4800 packs 2.5 times more shader processors and texture units compared to the last generations, whereas HD 4870 X2 doubles that number. In order to run properly, the two RV770 chips must be interconnected, which is done using a second generation PCIe bridge called PLX. It enables bidirectional x16 lines connection between the two cores, providing up to 10GB/sec bandwidth as well as additional 10GB/sec towards the PCIe slot. It seems like ATI had some additional plans for their card as they included another interconnection among the graphics cores using a chip called Side Port. It’s actually unused, or rather a disabled connection that would, if it was running, provide additional 10GB/sec among the cores.
Sapphire's card looks quite sexy in red and black color.
HD 4000 features a newer UVD (Unified Video Decoder) 2.0 engine than enables dual-stream decoding as well as 7.1 channel audio. In order to enjoy HD content, both dual-link DVIs are HDCP enabled, but in order to get HDMI with sound you’ll need the DVI-to-HDMI adapter that Sapphire ships with the card.
The box is as appealing as the card itself, and this is the first time we got 3DMark Vantage as a gift, as well as CyberLink PowerDVD 7 / Cyberlink DVD Suite. Of course, there’s also the Ruby ROM with a couple of little surprises and the user’s manual.