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Whats the diff w/ 128bit and 256bit ?

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ezcharlie

Member
Joined
Apr 7, 2003
Location
Philippines
was wondering how big the difference is w/ a 128bit and and 256bit VC?
for example a 5700 series and 5800 series?
or even a 4870/4890 vs 5700 series?
what are the benefits of a 256bit vc over a 128bit vc?
i'm planning to upgrade my 4850 1gb.
 

kvn864

New Member
Joined
May 9, 2006
Hi, what is VC? 256bit vc over a 128bit vc? You probably mean memory bus interface. Look at it as a highway between GPU and graphics memory on the card. 2 lines versus 4 lines. more bandwidth = better performance. It is more complicated in real life though, but you get the idea.
 

MattNo5ss

5up3r m0d3r4t0r
Joined
Aug 11, 2008
Assuming the same type of RAM, DDR3 or DDR5, on both cards. The memory clock on the 128bit will have to be twice as high as the 256bit memory clock to get the same bandwidth. For example, 2000MHz RAM 128bit GPU ~= 1000MHz RAM 256bit GPU in memory bandwidth.
 
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ezcharlie

Member
Joined
Apr 7, 2003
Location
Philippines
oh btw, if that's the case,
why have i noticed that the 5700 series is much faster than the 48/4900 series?
what's the new technologoy that makes them better?
 

BossBorot

Member
Joined
Jul 7, 2006
memory bandwidth usually isn't the most important thing in determining video card performance. Also gddr5 on a 128 bit controller offers essentially the same memory bandwidth that gddr3 does on a 256 bit controller.

Basically you wont see a sufficient bottle neck due to memory bandwidth when you move from your current gddr3 256 bit card to the 5770 which is a gddr5 128 bit card
 

doz

Member
Joined
Nov 30, 2002
Location
Las Vegas, NV
48/49 series is GDDR5 as well.

Besides that, a 4890 if faster than a 5700 series card, but the 57xx has DX11 support and isnt THAT much slower, which makes them appealing.
 

MadMan007

Magical Leopluridon Senior
Joined
Nov 28, 2001
Location
in a magical field
To put it another way - (all other things being equal which they never are ;) but..)

Total memory BANDWIDTH is what matters, not the 'bit-ness' of the interface. Bandwidth is a product of (bit-width)*(memory speed). Therefore a lower bit-width but faster memory can deliver just as much total bandwidth as a higher bit-width but slower memory speed.
 

kyussinchains

Member
Joined
Dec 27, 2007
Location
UK
I'm not sure where you got the idea that the 57xx series is 'much' faster than the 4870/4890 series..... the 4870 is generally faster in most games/apps, and the 4890 is noticably (ie probably over 10%) faster.....
 
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ezcharlie

Member
Joined
Apr 7, 2003
Location
Philippines
in other words, get a 5850 or higher to get
ddr5, 256bit, dx11, eyefinity and what not.
i was just trying to justify the price difference since 4870's are really cheap nowadays.
take note i'm in the phillipines so availability from newegg or jabtech etc is not an option.
 

Falkentyne

Member
Joined
Apr 9, 2001
If you're buying a video card for a young kid whos going to do nothing more than counter strike source and some free multiplayer online games, and homework, then a cheap 128 bit video card is fine. If you're going to have any intention of playing anything retail and semi new and demanding, then you had better get a 256 bit video card. :chair:
 

Neuromancer

Member
Joined
Oct 11, 2005
Location
Tau'ri
If you're buying a video card for a young kid whos going to do nothing more than counter strike source and some free multiplayer online games, and homework, then a cheap 128 bit video card is fine. If you're going to have any intention of playing anything retail and semi new and demanding, then you had better get a 256 bit video card. :chair:

Nope not what is being said at all.

Please reread the thread. New cards are 128bit and blow away older 256bit cards.

Now 128bit GDDR5 vs 256bit GDDR5... then you would take 256bit maybe. Problem is I dont think there is one.

Actually 256bit inflates the cost of the video card too much which is why some makers went with 128bit (less I/O on the core but better RAM ICs. instead of an expensive 256bit IO on the core, and not significantly cheaper GDDR3