ATI HD4870 & HD4850 Crossfire Performance Review

Performance Analysis

HD4870 Crossfire

The performance offered by a pair of HD4870 cards is simply stunning but with a price of around $540 in the best of cases, it doesn’t come cheap. To be honest with you, this configuration will blow a single GTX 280 straight out of the water and should be without a doubt the arsenal of choice for those of you with high-powered Intel-based systems. One important thing to remember here is that in some cases we experienced a fair amount of CPU bottleneck at anything under extreme resolutions and this was with a processor running faster than any stock-clocked CPU on the market today. This means that you will need some serious horsepower to really benefit from a pair of HD4870s in Crossfire if you are playing at anything under native 24” resolution with high AA and AF enabled.

There is however some minor sticking points about this setup that should be brought up right away. First of all while the performance may be quite good, we all have to remember that the R700-based cards are right around the corner. So, before you go this route make sure that you take a good, long hard look at what ATI has in store for us in the next little while.

There is also the small matter of some games just not benefiting much from Crossfire but we did not experience any of these cases in the games we tested. This goes for every combination tested here but more so when a setup costs you north of $600. At this point there isn’t a game out there that a single HD4870 doesn’t already eat for breakfast at 1920 x 1200 resolution even with AA and AF turned up quite high. So, while Crossfired HD4870 cards may put up some very impressive numbers, you should seriously weigh the benefits of $600+ worth of graphics cards against the negatives before taking the plunge.


HD4850 Crossfire

In our opinion a pair of HD4850 cards really hits a sweet spot in the price / performance category. This combination offers performance which in most cases is equal to or greater than that of a GTX 280 while retailing for less money. Even though it may not be quite up to par in notoriously Crossfire-hating games like Crysis, it literally shines everywhere else.

To be honest with you, if you have a Crossfire-enabled motherboard with an X48, X38 or P45 chipset and are on a bit of a budget, we would recommend going with Crossfired HD4850 cards. The price is right, the performance is there in spades and you will pretty much be guaranteed smooth performance in upcoming games. We feel that this is the combination which will bring Crossfire to the most customers possible and indeed there has already been numerous people in our forums and others who are leaning towards buying a pair of these cards. Without a doubt, we highly recommend a pair of HD4850s in Crossfire over any other dual card solution we tested here today.


HD4870 + HD4850 Crossfire

Even though the internet is a great place to find a ton of information, some of it isn’t always accurate and while some claim to have seen performance increases of mixed Crossfire over a pair of HD4850 cards, it wasn’t meant to happen. While performance was marginally better (and we are talking about a difference which was well within the usual margin of error when benchmarking) than a pair of HD4850 cards in Crossfire, we really wonder what the use of mixed Crossfire is.

The problem with this type of configuration is the fact that the faster of the two cards will always downclock to keep pace with the slower card. This means that the core speed of 750Mhz and blistering memory speed of 3.6Ghz on a HD4870 means absolutely squat when paired up with a HD4850 running at 625Mhz / 1.986Ghz. We have a screenshot below to accurately illustrate what is happening as we looped a 3DMark 06 Batch Size test which should theoretically load both cards at 100%.


As you can see, the HD4870 on the top two GPU-Z screenshots has less than 100% load on both the GPU and the memory while the HD4850 (bottom) easily hits 100% when asked to render.

In all reality, we really can’t recommend going this route and can’t figure out why someone would really want to in the first place. Granted, if you win a HD4870 in a contest and then don’t want to spend the money to pair it up with a similar card this is a perfectly fine route but other than that, what’s the use? You could buy a pair of HD4850 cards and have the same performance for $100 less.