Sapphire HD 3870 X2 Review

The end of the past year was crucial for the both leaders in videocard business - NVIDIA and AMD. NVIDIA managed to release their new G92 core and the 8800GT based on it, at the end of October. Few weeks later AMD released RV670 or as it's more known to the end user - HD 3870. Bad thing for AMD was not only that they were late, but also that their new card was weaker than 8800GT. NVIDIA rushed and released their new G92 based 8800GTS 512MB, being twice cheaper than the older 8800 Ultra, but with equivalent performance it left the competition defenseless in the high class card segment. That's why AMD took a bit different approach... two RV670 chips on one board - connected in CrossFire. Construction using the name R680. Did AMD managed to do it right? In order to find out we compared the new Sapphire HD 3870 X2 to few other cards in the same class.

HD 3870 X2, two cores, technical point of view...

Although when AMD released the Radeon HD 3000 series, a statement that the suffixes in card names are history was made, it is obvious that they have returned with Radeon HD 3870 X2. The card is codenamed R680, but it's just two RV670 cores on a single PCB, with integrated CrossFire bridge, sharing 1 GB (2x512MB) GDDR3 memory. As you might remember HD 3870 had GDDR4 memory working at 2.25GHz and a single RV670 core at 775MHz. Since we can't remember any HD 3870 cards that couldn't go at least 850-860MHz of core overclock, it is apparent that this was not gone unnoticed by AMD either, so they set the core at 825MHz for each core in the new dual core card. The memory is more interesting though - now instead GDDR4 at 2.25GHz, we have 1.80GHz GDDR3 - rather conservative and unexpected. The reason as you guessed it is the price. In the end HD 3870 X2 comes at a great prise, as long as we assume it's competing with 8800 GTX / Ultra. For the record - in Bulgaria 8800 GTX / Ultra is sold for about 1150 leva (~575 Euro) and 1300 leva (~650 Euro) respectively, While the price of HD 3780 X2 for the end user is just under 400 Euro, tax included.

The next thing to be noted is that unlike HD 3870, the new card isn't PCI-E 2.0, but a PCI-E 1.1, just like R600. That apparently is due to the bridge connecting the two cores and the PCI-E slot. The bridge is consisted of an PLX Technology PEX 8547 48 passage chip with 3 configurable channels. Logically AMD put 16 passages for each channel (x16), so in this way between it an each of the chips we have x16 connection, while the chips themselves share a x16 connection to the PCI-E slot on the motherboard. After a blunt inquiry as to why AMD used the PCI-E 1.1 standard instead of the 2.0, AMD's reply stated only that the difference between PCI-E 1.1 - 2.0 is under 1%. Irony here is in the fact that prior to that cart AMD was constantly bragging about the PCI-E 2.0 support of their HD 3800 family cards.

But let's try to answer the big question here - are two cores on a single PCB a good thing? If it is to be true and such implementations were performing well, then why are there so few cards based on it? This isn't the first attempt of ATI for a dual chip card, they are not even the ones to thought about it. The first card ever to de of that design was Quantum3D Obsidian2 - based on two Voodoo 2 chips. The more "vintage" gamers amongst you will never forget the emblematic Voodoo 5500. History remembers also ATI’s Rage Fury MAXX, but after the the SLI and later Crossfire introduction, the partners of NVIDIA and AMD had presented their own retail implementations. NVIDIA even have attempt at quad SLI a while ago, with two dual core OEM 7900GX2 cards, perfecting it later in 7950GX2.

Still the question hangs. Why are these cards easily counted on the fingers of one hand? Why is still the single chip so popular? Simple really. Even if we forget about the manufacturing cost of such monsters, we all know that the cards are dependent upon the drivers developed for them. And even though many games are created with the idea to benefit from SLI or Crossfire, this is not always the truth and even when it is it still comes down to properly optimized drivers for each game. Bottom line is that it's costly to write quality drivers before the release of each iconic game that has the chance of becoming standard for testing of modern cards. There is another thing too - if you play something a bit older or less know, thing never intended to run on multiple cores, thing unlucky enough not to make the list of "blessed" Crossfire or SLI games, there is a strong chance you'll be having problems. And even id you don't it still would perform as on single core. Very good example for problematic software support of just such type of hardware is the GeForce 7900GX2/7950GX2, which for a long time after the release of Windows Vista had no proper drivers. They had to work as plain 7900/7950 or even worse. Then a set of БЕТА drivers came, but still a direct support from the moment you plug the card in is to be seen.