Alex Medick

VRAM capacity often dominates discussions around GPUs for any developer looking at using AMD products for their projects. While other teams might focus on bigger picture items (costs, timing, etc) the reality for engineering teams brings much more detail and opportunity cost comparison to the table - things like bandwidth, memory type, latency, and compression techniques all play critical roles in performance. Today we’ll dive into AMD’s VRAM implementations, how they differ, and what those diff

More Than Just Capacity:  How AMD VRAM Impacts Performance

VRAM capacity often dominates discussions around GPUs for any developer looking at using AMD products for their projects. While other teams might focus on bigger picture items (costs, timing, etc) the reality for engineering teams brings much more detail and opportunity cost comparison to the table - things like bandwidth, memory type, latency, and compression techniques all play critical roles in performance. Today we’ll dive into AMD’s VRAM implementations, how they differ, and what those differences mean in real life.


Memory Types and Their Impact

Let’s first start with AMD’s GPUs different memory types: GDDR6 and HBM2(e)

 * GDDR6: Mostly used in your everyday GPU - it delivers high bandwidth at a relatively lower cost for folks. It runs on a 16n prefetch architecture, meaning each access fetches 16 data words per clock cycle, improving efficiency.
 * HBM2/HBM2e: Your GPU type found at the desk of your not-everyday-person - higher end GPUs.These are your High Bandwidth Memory stacks bringing massive bandwidth at lower power consumption, at the cost of being more financially expensive. You would want to use this in something like AI training.

Example for Startups: If you're developing a deep learning tool that processes massive datasets (like AI video generation), an HBM2e-based GPU could significantly speed up performance. Of course there is opportunity cost to evaluate as well, but may save you runway in the long term in that it may be a larger upfront investment but will save you money down the line in terms of speed you can operate, time to market, and avoiding potential down time. You don’t want to be the team missing a window of opportunity because you are processing at exponentially slower speeds than competitors.


Why Bandwidth Matters

Memory bandwidth, in its most simple form, is how fast data is moving inside a GPU. For general purposes, it is: Effective Memory Clock × Bus Width × Transfers per Cycle

You can see it in real life with two AMD GPUs:

 * RX 6700 XT (12GB GDDR6, 192-bit bus) = 384 GB/s bandwidth
 * RX 6800 (16GB GDDR6, 256-bit bus) = 512 GB/s bandwidth

When deciding which GPU to go with, a good general rule is the GPU with a wider bus and higher bandwidth will handle heavy tasks much better. Like a car for example, a truck is better at delivering and moving heavy loads in its bed compared to the trunk of a normal sedan.


AMD’s Secret Weapon - Bandwidth Amplifier

Knowing there could/would be bandwidth limitations, AMD developed a secret weapon to level things out: Infinity Cache. In short, it’s a high-speed buffer to reduce the need for frequent VRAM access.

So we can look at two of AMD’s GPUs using Infinity Cache

 * RX 6950 XT (256-bit bus, 512 GB/s bandwidth, 128MB Infinity Cache)
 * RX 7900 XTX (384-bit bus, 960 GB/s bandwidth, 96MB Infinity Cache)

Even though the 6950 has a narrower bus, it can still compete with the 7900 since its Infinity Cache helps keep important data close to the GPU. This can help early stage startups save on cost in drastic ways, even on the surface in that the 6950 is over $300 cheaper for one.

If you were to build an AI chatbot that processes messages in real-time, a GPU with Infinity Cache can reduce response lag and get the job done competitively like any other player on the market.

Lastly, it’s important to know Infinity Cache is not a magic wand that will completely compensate for a more narrow bus in all workflows. In some situations you may just need more outright bandwidth (like training large models where tons of data is constantly accessed). Cache may not outperform or compete where sheer bandwidth is needed.


The Role in Real-Time

A big piece of the puzzle here as well is whether or not your project is in real time or not. Think live-streaming, trading, or imaging for example. In these situations, VRAM speed and efficiency are just as important as its own outright capacity. Here latency is often a bigger bottleneck than sheer memory size.

For example, if you're developing something that requires rendering high-resolution images on a moment’s notice, low-latency VRAM with high bandwidth (such as HBM2e) could drastically improve responsiveness.

However on the flip side, if you and your team are building something that requires more focus on storing large assets rather than rapidly processing them, a high-capacity GDDR6-based GPU with Infinity Cache might be a better alternative.


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More Than Just Capacity:  How AMD VRAM Impacts Performance

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More Than Just Capacity: How AMD VRAM Impacts Performance

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More Than Just Capacity:  How AMD VRAM Impacts Performance