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I was looking at this specific GPU named RX 550 / Radeon 550. Later I found out that is two variants. 2GB DDR5 and 4GB DDR5.

Then I realized one more difference: 2GB variant has 64 bit memory interface and 4GB has 128 bit.

Price difference is not a problem to me. It's not very significant.

I also checked official specifications especially about memory which shows the memory interface differences:

2 GB variant:

enter image description here

4 GB variant:

enter image description here


Why I feel 4 GB variant can not be a good choice:

I read some comments on Reddit that this GPU is not powerful anyway. So it won't be able to use 4GB anyway.

Some people say 128 bit is better than 64 bit as it will allow faster speed.

Maybe 128 bit memory interface is only used because it has 4GB memory? It has nothing to do with a fact like 128 bit is better than 64 bit? I'm not sure. That is also what I'm curious about.

Given all that, which one would give better performance on same PC for same games? And do 64 bit and 128 bit difference matter in this particular case?

2 Answers 2

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https://www.videocardbenchmark.net/high_end_gpus.html

Radeon RX 550 @ 128-bit 4gb ddr5 is higher up with a score of 2718, priced at $158.

Radeon 550 @ 64-bit 2gb ddr5 is 2nd from the bottom with a score of 1958, priced at $99.

RX550 = 50watt, Dx 12.0, pcie 3.0 x8, core clock 1100 mhz, memory clock 1750 mhz, opengl 4.5, overall rank = 406

550 = no data, Dx 12 says 14 frames/sec.

Why I feel 4 GB variant can not be a good choice...

the 4gb variant is the better choice between those specific two, as benchmark scores (if u believe them) also point out. The redit rationale about not being able to use all 4gb anyway is ridiculous. If it uses 1mb of video ram or 1000, 128-bit will operate twice as fast as 64-bit, simple as that! Where the rubber meets the road is in the comparisons between clock speeds of everything, which i cannot find for 550. But like with all other graphics cards makes/models the variants are always faster... usually the result of minor overclock, and sometimes extra ram.

The RX550 is better than 550; the 550 will not outperform the rx550.

There are many better cards than RX550.

Radeon RX6400 @ $160 second from top at best value chart: https://www.videocardbenchmark.net/gpu_value.html

the biggest factor may be in 550 not supporting latest versions of openGL and DirectX where the RX550 will, so that reason alone will likely make rx550 better than 550. The "550" probably went obsolete a few months after release when AMD got the rx550 selling, now the "550" is just obsolete already built cards that haven't been recycled yet where sellers are just looking to offload them.

what i could find: https://www.techpowerup.com/gpu-specs/radeon-550.c3407

550 shows same clock speeds as RX, so no, no way it'll ever be better than rx550; all amd probably did was update the memory bus to 128-bit and double the vram circa 2017 to compete with market competition.

https://www.techpowerup.com/gpu-specs/radeon-rx-550.c2947

and given the fraud in the graphics market, hard to tell 550 from rx550 from 560 and 570; what you find as "rx550" advertised as 128-bit 4gb ddr5 you might get a 64-bit 2gb card so be careful with end of life stuff like that.

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Because the GPU is not very fast, you must avoid other bottlenecks when possible. Since that 64bit gpu has about the same memory speed as an integrated graphics card, I would personally avoid it (those are heavilly bottlenecked by RAM speed). If the 4GB card is about the same price, there is no reason to go slower.

BTW the reddit page is wrong about that not being able to use 4GB. Ram is measured in GB for a reason, and if you dont have enough, it will slow down (thats why I want 32GB ram on a Ryzen 3). If an app requires 4GB on a 3070, it will require 4GB everywhere.

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  • Would there be any performance difference if both were 2GB but one had 64 bit and other 128 bit?
    – Vikas
    Commented May 2, 2022 at 6:12
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    Yes, because there is also something called memory bandwidth. Double the memory bandwidth can have a 30% performance increase. Since the 128bit version has double the memory bandwidth, that alone could get you a performance boost
    – Irsu85
    Commented May 2, 2022 at 13:25
  • Okay. If you know, this 64 and 128 bit difference is visible physically on GPUs? Or you only know digitally when you plug them in?
    – Vikas
    Commented May 2, 2022 at 14:12
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    If the model number does not give it away, you can only see it easily in software like GPU-Z or AMD Radeon software
    – Irsu85
    Commented May 2, 2022 at 16:18

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