What does bit do for video cards?

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nightly1029

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I was looking over video cards and found 1280MB 320-bit for a little over $200. Then I found a 900 MB 448-bit for the same price. What's the advantage of sacrificing GPU memory for more bit? And are 448/512 bit video cards worth the price, Or am I better off stacking as much memory as I can?
 
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Edited my above post, but its due to the processing ability of the GPU not the memory bus tied to it that gives it the performance edge. There are cases of cards with large memory buses that are actually quite weak, the GT 330 has some models with a 256 bit memory bus, but due to the underpowered GPU its beaten by many cards with only 128 bit memory buses which is why the memory stats dont tell you much about the overall performance of the card.
That actually tells you absolutely nothing about the performance of the card, all it tells you about is the memory which is only a small part of the performance of the card. Which cards are you looking at? The GPU itself makes a much bigger difference than the memory interface does.


As for what the bits do, the memory bandwidth is the effective memory clock speed times the bus width, so a wider bus can help to improve performance but only if memory performance was the limiting factor, if the GPU is too weak to push through the data fast enough it doesnt matter how much bigger you make the memory bus it wont matter.
 
forget about bits what is more relevant is "total memory bandwidth" which includes, bits and mhz. amount of bits does not dictate a graphics cards performance, there are things like GPU core speed/shaders/texture units/. You obviously know little about computers so ill give you a few hints. If you want to ask a question please state what you are trying to achieve eg are you planning to play games?. list your current system specs - there is no point getting a top end video card if your power supply or the rest of your computer is not up to spec. Read reviews of video cards to help you chose which one is fastest, they are the only true indicator of performance.
 

konzine

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nightly1029

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I do play a lot of games, Yes, And say what you want about my knowledge of computers, But I'm not leaping into this buying a $300 video card while having a 400 watt power supply. You obviously know little about common courtesy, So I'll give you a few hints. When you're trying to be the cool guy know-it-all, Don't be so smug about it. It makes you look like a liiiittle bit of a douchebag. I went through the Tomshardware performance charts and it seems the higher memory video cards are out performing the lower ones with higher bits, So I made a thread asking why that is.
 

nightly1029

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I'm comparing a Nvidia GTX 260 Twin Frozr vs. a Nvidia GTX 470 Fermi.
 
There we go, that is a much different and much clearer question, the GTX 470 is vastly superior to the GTX 260, not because of the larger memory bandwidth, but instead because of the significantly higher processing power on the GPU itself, they just tied it to a larger width bus to avoid memory bottlenecks.
 

nightly1029

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Alright, Can you explain why? The price is basically the same.
 
Edited my above post, but its due to the processing ability of the GPU not the memory bus tied to it that gives it the performance edge. There are cases of cards with large memory buses that are actually quite weak, the GT 330 has some models with a 256 bit memory bus, but due to the underpowered GPU its beaten by many cards with only 128 bit memory buses which is why the memory stats dont tell you much about the overall performance of the card.
 
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nightly1029

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Thanks for the thorough answer. So when buying a video card, Basically what I'm looking for is the highest memory clock speed?
 
Nope, when buying a card i suggest just paying enough attention to the specs to know if its factory OCed and exactly what model it is, then go look at some benchmarks for it and see how it does. It is incredibly difficult to figure out how well a card will perform relative to others by specs alone when they are not of the same family, for example you can expect a GTX 480 to beat a GTX 470 because its got more shaders and more of everything else to back it, but trying to tell whether a GTX 275 or a GTX 460 1GB is faster is difficult to do due to the architecture changes inside, some designs get more done per clock cycle than others so the clock speed and shader count still doesnt tell you just how much data it can crunch so i always recommend benchmarks for what you want to use it for over specs, i dont even know the specs for most cards off the top of my head, but i know where to find benchmarks for them in different applications.
 
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