Have you ever taken your shiny new graphics card home only to be disappointed at how you
can't turn the settings up as far as you want in some hyped up AAA game?
It turns out that in many cases, this isn't because the GPU is underpowered, instead you
might not have enough video memory, or the amount you do have might just be too slow.
But the next generation of VRAM, GDDR7, promises to help alleviate some of these issues with
never before seen bandwidth. This is a big deal because of the rapidly increasing demands being put on gaming PCs,
where the high resolution textures and complex visual effects of big name titles can overload
all but the highest end hardware, meaning you need enough high speed VRAM to hold all
that data that the GPU is being asked to process. In fact, one of the more common gripes from folks who bought the RTX 3070 on an upper
tier GPU was that it only came with 8GB of VRAM, resulting in performance issues and
graphical glitches in games that the GPU itself could probably have handled.
Enter GDDR7, which is expected to bring us a huge bump in memory bandwidth without sucking
down more power, which is great news for those who just want to turn up the settings but
are already fighting the rising power draws of Neurogen graphics cards.
We're talking 36GB per second per PIN.
Once you translate this into a card with a 2.6-bit wide memory bus, that is a full 1.15
terabytes per second of throughput. To put that into perspective, the RTX 4080 only has around 700GB per second of memory
bandwidth, so all that extra space in the pipe could help demanding titles even without
adding more actual VRAM. But what exactly is the secret sauce that allows GDDR7 to reach these new heights?
GDDR7 uses a little trick called PAM3, and that's not the stuff you spray on your
pan so the tater tots don't stick. It's Pulse Amplitude Modulation.
In PAM3, each clock cycle can have 3 voltage states, positive 1, negative 1, or 0.
Each sequence of 2 cycles encodes 3 bits of data.
For example, a negative 1, followed by a positive 1, corresponds to the bits 0, 1, 0.
In this way, each clock cycle encodes 1.5 bits of data instead of just a single bit.
But you're a savvy viewer, and maybe you already know that the current top-end video
memory, GDDR6X, actually supports PAM4.
I mean, isn't that better? 4 is a bigger number than 3.
I think. Maybe. Well, it's only better to a point.
PAM4's encoding scheme actually delivers 2 bits per cycle, making it faster than PAM3
on paper. But there are some drawbacks. More possible states per cycle means that there's a greater chance for errors in data
transmission. And to compensate for this, you need more error correction functionality as well as
a new physical design and different memory controllers.
All of these things increase both the cost and the power consumption, not to mention
that the GDDR6X can only operate in PAM4 mode when data is being sent in 8-byte bursts
instead of the more standard 16-bytes, meaning GDDR6X can actually have less bandwidth overall
in real-world scenarios. Put all this together, and GDDR7 is supposed to give us more bandwidth while being more
energy efficient than GDDR6X, not to mention it can switch off PAM3 when it's not needed
and instead use the 1-bit per cycle NRZ scheme.
But when are we actually going to see our graphics cards? The answer is probably late 2024, as that's when we're due for another major GPU refresh
from both AMD and NVIDIA. And reports are already out that NVIDIA may be planning to use GDDR7 for its upcoming
RTX 5000 GPU series, which I will definitely be buying as long as I can sell a couple of
my organs first. Thanks for watching guys, like, dislike, check out some of our other videos, and comment
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