If the RTX 4090 and RX 7900 XT and XTX have the same amount of GDDR6, why does the 4090 outperform the 7900?


I’ve been looking at upgrading my PC in a few months, not to anything this powerful (but a man can dream) and in looking at GPU comparisons I see that the 4090 tends to be streets ahead of the RX 7900’s in terms of performance. Why is that if they have the same amount of memory?

In: 2

Architecture and optimization.

The two chips work in different ways. One is like a V8. The other is like a turbine. There’s nothing wrong with either design and both can make a car go, but they operate differently.

Because they work differently, you have to write code that works on both. If you have game devs writing code designed for a turbine input, then you will find the turbine works better.

On the other hand, there will be other case where a turbine might not be the best solution. In that case, you might see that other game work better on th V8.

Connected with this is what you’re trying to do with it. One chip bet heavily on ray tracing. The other on speed without ray tracing. You just get different results.

I ended up with a 6750 that was on sale. It’s certainly the most blazing card Ive ever owned. I’m running 60gps on ultra 1440p all day, which is better than I was expecting.

Because they have different processing units. You know, the RTX 4090 and the RX 7900 part of their name. Just like how RAM is just one part of what describes the compute performance of a PC, the (V)RAM is also only one part of what makes a GPU.

Because memory is not everything. It’s just like a car. Just because two cars have the same engine doesn’t mean they will be as fast. If one is heavier the other will be faster.

That’s like wondering why one car with an I4 engine with two turbos isn’t faster than a W16 with a single supercharger. I hope that explains everything you need to know.

Performance does not scale smoothly with memory ammount. It is usually either “it works” or “it doesn’t work” with not much in between.

Memory is used to store data. Either you have enough memory and it works fine. Or you do not have enough memory and you have really bad time.

If the card doesn’t have enough memory the game may simply crash or it may have ungodly stuttering because it has to load and unload data from RAM or hard drive.