In this column we will show you how easy it is to pick out the right graphics card for your gaming purposes. We will also try to clear the air surrounding the graphics market and help make your future upgrades painless when it comes to picking out what you want.
Graphics processors haven’t changed all that much in the last three years. Although we’ve seen an architecture shift into designs that are optimised for more parallel code, they still follow mostly the same process; the game engine tells the GPU drivers what it wants, the GPU does the math, the resulting code goes through layers of drivers and other software before eventually displaying a single frame on your screen.
But not all graphics cards are made equal. Some that fit into cheap budgets offer lackluster performance for games, while others may be overkill (wasted money) for your intended application. Balancing out your needs and requirements with what’s on offer can be tricky, especially if you’re working on a tight budget.
So lets take a quick look at things to take into account when shopping for a new graphics card.
Resolution limits everything
Your monitor’s resolution is a major factor in your choice because not only does it dictate which cards you need to look at, it also limits you in terms of how much performance you’ll be able to get.
For example, running a game at 1280 x 720 resolution means that you can get away with a smaller frame buffer (RAM on the graphics card) of 1GB and your card doesn’t have to be very powerful to drive this resolution. You can also get away with integrated graphics and cheaper, low-end cards will be perfectly suited to this resolution.
Moving up to 1080p necessitates a larger frame buffer of 2GB or more because there is more detail to resolve. You can get away with a graphics card with 1GB of RAM but you will need to lower all of the settings.
If you’re not running a 1080p monitor, don’t spend more than R2,000 on a graphics card. If you are running a 1080p monitor, any graphics card over R2,000 will suffice.
For resolutions higher than 1080p, tack on an extra R2,000. Playing on a 1440p or 1600p monitor? Don’t spend less than R4,000. Do you own an UltraHD 4K monitor? Budget within the R6,000 price range. A Radeon HD7970 is currently the minimum requirement for that resolution.
However, the advice I’ve just laid out falls flat in the face of games with texture and graphical modifications and triple-monitor setups. These situations are rather niche though, and if you are doing those things you should already be aware of how those requirements change your options.
Memory bandwidth and bus size
The memory embedded on your GPU is also important because it directly impacts performance. Lets take the Geforce GT640 as an example. It ships with 2GB of DDR3 memory as standard on a 128-bit memory bus.
The memory bus limits how many memory chips can be fit onto a GPU and how much bandwidth is available. If we were to increase the bus size to 256-bit, we would see some modest performance improvements, but you would then be limited by memory speed and you’d need more DDR3 chips to increase bandwidth.
GDDR5 is on average twice as fast as GDDR3. You have less performance limitations from the bus width and your graphics card has space to stretch its legs. However, GDDR5 memory is more expensive, so the trade-off is moving down to 1GB of memory on the smaller bus.
As a rule of thumb, a graphics card with GDDR5 is preferable to one with DDR3 and should be your first consideration. Cheap cards with 2GB or 4GB DDR3 frame buffers will not give you more performance.
Memory bandwidth is also directly tied into performance at different resolutions as well. If you had the 2GB GT640 on a 1080p monitor, it would be twice as slow as the 1GB GDDR5 version. But a graphics card that doubled the bus and the memory size, to 2GB GDDR5 on a 256-bit bus, would be even faster.
Moving up the resolution ladder also raises the memory and bus size requirements. At 1080p, 2GB GDDR5 and a 256-bit bus is recommended for a good experience. This increases to 2GB and 384-bit at 1440p and 3GB and 384-bit at UltraHD 4K.
To Physx or not to Physx?
Physx is an API (application programming interface) designed by Ageia, a hardware company bought out by Nvidia in 2008. It enables Geforce graphics cards to render cloth effects, simulate the behaviour of particles accurately, add more objects into the game world, simulate waves and the ocean, and in general, make your gaming experience slightly more immersive because things look and work the way you’d expect them to in real life.
However, GPU-accelerated Physx only runs on Geforce and Quadro graphics cards, which means that using an AMD graphics card will block out those features. In addition, a number of games feature Nvidia-only optimisations that are not exposed on Intel or AMD graphics cards. The choice of whether to aim for Physx or not is a personal one, although it does impact performance slightly and makes some game visually more attractive.
Tying it all together
I haven’t hit on the other details like stream processor count, pixel and texture fill-rate, overclocking, or even Mantle. The way AMD and Nvidia manufacture and position their cards means that the more money you spend on them, the better your in-game performance will be.
This means that when moving from a Radeon HD7770 to an HD7850, or a GTX650 Ti to a GTX660, you won’t need to worry about the other details because you’re guaranteed to get a performance boost.
Whether or not that boost is worth the price you’re paying for it, however, is exposed through benchmarks. You’ll have to decide for yourself if the boost is worth it by reading a few reviews and looking at benchmarks of games you’re interested in.
In addition, many gamers don’t upgrade frequently, opting to buy a PC that lasts them a little longer before it becomes necessary to buy new hardware. Always buy the best hardware you can afford because it has to last you until your next upgrade, possibly longer if no new hardware challenges what you already own.