GDDR3 256bit vs GDDR5 128bit

[Miez]

Hi guys.
I'm about to buy a new graphics card and I have to chose between GDDR3 256bit and GDDR5 128bit and I'd like to know which is better and does my motherboard support GDDR5?
I'll come back with the model names later..

CPU - AMD Athlon II X3 455 Processor 3.30 GHz
RAM - 4.00 GB Dual-Channel DDR3 @ 665 MHz (9-9-9-24)
OS - Windows 7 Ultimate 64-bit Service Pack 1
Motherboard - ECS A780LM-M2 (CPU 1)
Graphics - ATI Radeon HD 5450 (Sapphire / AMD)
HDD - 466GB Seagate ST500DM002-1BD142 ATA Device (SATA)
Optical Drive - TSSTcorp CDDVDW SH-222AB ATA Device
Audio - VIA High Definition Audio
Network - Realtek PCIe FE Family Controller

 

[Core]

It's not a question of support; if you have the right slot for the card (PCIe, etc), sufficient cooling and power supply, you're good to go. Your motherboard doesn't care about the type of memory the GPU uses.

As far as the other thing goes, GDDR5 128bit has the same bandwidth as the 256bit GDDR3; you're better off with the GDDR5 card.

 

[Miez]

Oh.. alright thanks mate, I forgot to state that I need a good graphics card for gaming so I'll be able to play high demand games..

 

[Miez]

Which of these cards should I buy?
Asus AMD Radeon HD6670, 1024MB, GDDR5, 128bit, DVI, HDMI, PCI-E
Sapphire AMD Radeon HD6670, 1024MB, GDDR5, 128bit, DVI, HDMI, PCI-E
MSI AMD Radeon R7750, 1024MB, GDDR5, 128bit, HDMI, DVI, PCI-E
ATI Radeon HD4850, 1024MB, GDDR3, 256bit, HDMI, PCI-E
Thanks in advance..

 

[Kougar]

That's easy, of those you listed most most definitely get the R7750 GPU

The 4850 is really old technology now, and the 6670's are last generation cards that don't perform as well. Here's a comparison: http://www.anandtech.com/bench/Product/535?vs=613

 

[Digerati]

As far as the other thing goes, GDDR5 128bit has the same bandwidth as the 256bit GDDR3; you're better off with the GDDR5 card.

That assumes all else is equal. Twice the bus width can certainly result in a MUCH larger bandwidth - potentially twice the size. 128-bit @ 1GHz equals the bandwidth of 256-bit at 500MHz. Clearly you can see increasing the speed on a 256-bit bus can result in higher bandwidth.

256-bit cards take much more power, generate quite a bit more heat, but as noted, don't necessarily result in more FPS. So getting a 256-bit may or may not result in better performance.

The fact of the matter is, when comparing cards, you should look at the overall "memory bandwidth" specs, and not pay much attention to bit rate.

See: http://www.ehow.com/about_6767000_128-256-bit-graphics-card.html

 

[TrainableMan]

Well it's also important to know what you want to do with the card. Unless you are a gamer, any of those cards will work.

If you are a gamer then, besides the stuff mentioned, depending on the level of DirectX support you need, you may need one of the newer models, so check the requirements on any new games you are planning to buy.

And if the card you choose requires more power or an extra connection you can't supply then you would also end up having to upgrade your PSU.