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Graphic Cards

by DSR17
July 12, 2005

We get many posts here at Help2Go asking for Graphics Card advise, memory size, clock speeds, memory interface etc. In this article we will look at all the different aspects of the cards and discover what they actually mean and how they affect performance so you can make your own informed decision rather than us just giving you a link to a card on newegg.

Designers and Manufacturers
There is currently a lot of confusion between who makes and designs graphics cards. Basically, there are two main companies that design the chips that go onto graphics cards, ATI and Nvidia. Once these companies have designed the chips, they pass them onto lots of other companies such as Sapphire, Asus, Leadtek and Inno3D to actually assemble the cards. The end result is similar to any computer, not all Pentium 4 3GHz computers are the same. Similarly, not all manufacturers extract the same thing from the chips so not every 9800 is exactly the same. I would recommend going with a well know brand but other than this don’t pay too much attention to who made the card, look at the specs.

PCI, AGP or PCI-Express
While this is a minor point that is usually determined by your existing motherboard, it could be a factor if you are building a new PC.
PCI is the oldest type of graphics card and as such is rarely used anymore. The range of PCI cards are very limited and concentrated at the low performance end. This may be your only option if you have a very old card but don’t expect very good resolution, detail or frame rate at all.
AGP comes in various flavours (2x, 4x and 8x) the only difference being the transfer speed with the main system bus. Always go for 8x if your motherboard is compatible. If it isn’t, many 8x cards will run on 4x boards but at the slower speed, check the specific card specification for details of this. The main advantage AGP has over PCI is that it has it’s own dedicated data connection with the main system bus (CPU and RAM). This means that your graphics processing doesn’t have to wait in line with your Sound Card or Modem and hence can be processed much faster.
PCI-Express (or PCI-E) is the latest format of graphics cards. Despite the name this is actually a new type of card, based around the PCI. Like AGP, PCI-E benefits from it’s own dedicated data connection with the system bus but also has a much higher bandwidth capacity than AGP. New technology with PCI-E also means it is possible to run two graphics cards in tandem for twice the gaming power. Pioneered by Nvidia, this SLI technology sounds great but will cost you an arm and a leg so unless you have money to burn and a hunger for 100’s of frames per second I suggest sticking with a single PCI-E card.
If you only have an AGP slot and only want moderate to high graphics don’t worry about forking out for a new PCI-E motherboard but if you’re building from scratch I would lean this way, especially for future compatibility.

OEM and Retail
It is also worth noting the difference between "OEM" and "Retail" cards. While OEM cards are a lot cheaper, they are supplied without boxes or manufacturer warranty. While this means if the card goes wrong you will not be able to phone up Asus or whoever to fix problems such as resolution or other minor problems, if the card is broken and will not work at all, they have to exchange it BY LAW. Some are not willing to pay the extra for the fancy box and warranty for a physically identical card but it is up to you should you choose to be unsupported.

Also, “refurbished” cards are cards that had a fault with them that were sent back to the manufacturer to be repaired. These repaired cards can no longer be sold as new so are sold off cheaply. Very similar to OEM so you could land a great deal if you don’t mind a second hand card.

Memory Interface
Probably the most important factor when choosing a card is the memory interface.
The memory interface is the number of “bits” that are transferred at a time. A “bit” is basically a slot for a binary number to go (a 0 or 1). Hence, the greater the number of bits, the greater the value being transferred can be. The interesting thing with binary is how much an improvement 128-bit is on 64 bit. While with 64 there are only 64 slots for a 0 or 1 to fill making a total of 2x10^19 possible values, 128 bit means a possible 3.5x10^38 values, that’s nearly 2x10^19 as many values.
While the performance increase isn’t quite this significant you get the idea. 128-bit is a lot better than 64-bit. The minimum you should be looking at is 128-bit if you do any modern gaming. 256-bit is usually reserved for the higher end cards, but is well worth it if you can afford it.

Memory Size
While this is not that important, you need at least 128MB. The reason this is less important is games only take up a certain amount of memory. If you have an excess amount of memory (say 512MB for a low end game) you will actually end up slowing the game down as the graphics card will have to sift through a larger memory bank to get the required information and hence take longer. Obviously this is exaggerating a bit but it is why only the very high-end cards have 512MB as they have very fast memory clocks to compensate.
If there is only $5 or $10 in it, I would go for 256MB, but be aware this is not the be all and end all of performance.

Clock Speeds
There are two type of clock speeds, memory and core clocks. This is really where the performance of the card comes from if the memory interface and size are the same so, the higher the clock speed, the higher detail you will be able to get and your frame rate will increase. The clock speed is how many cycles the Memory or Core (GPU or Graphics Processing Unit) processes per second. The Memory clock is almost always higher than the Core clock so don’t be put off by this.

Pipelining is a feature of the GPU, this basically means it chops up the data into smaller, more manageable chunks and then processes each bit by a specific section of the processor. This is sort of like specialisation in a factory. Moderate cards will have around 4-8 pixel pipelines while high-end cards will have between 8-16. These can really boost performance but usually go inline with all the other features so its not worth bothering too much about. Simply, the better the card, the more pipelines it will have.

Frame Rates
A quick note on frame rates, for a game to appear to be running smoothly you should have a minimum of 30fsp. Any less than this and you will start to notice lag (very undesirable in a fast shoot em' up game). I suggest downloading "fraps" (available here) to check your frame rates in games and decrease detail levels or resolution if you often run under 30fps.

Shopping For a Card
I find the best way to shop for cards is to enter either AGP or PCI-E in the search box and then sort by price. Display as much detail as you can on the results page and scroll down to around your budget. Open up a lot of cards in that area, above and below and gradually compare their specs, getting rid of them one by one. If you are stuck between a few, you can check out some benchmarks. The most important test to look at is the Frame Rate tests in games similar to those which you will be playing. Tom’s Hardware Guide here has yearly round ups of all the major graphics cards, so is well worth a look. The VGA charts are the overall comparisons.

While this rings true for all computer hardware you should keep your graphics drivers up to date. Graphics Cards companies (mainly ATI and Nvidia) are constantly developing new drivers for all levels of their cards and keeping up to date will help you get the most out of your card and minimise lock-ups and hangs.

Sorry if all this is a bit overwhelming but as you can see, there is quite a bit to consider. Happy gaming!

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