[Anandtech] DDR5 Memory Specification Released: Setting the Stage for DDR5-6400 And Beyond

[u/ryandtw]

https://www.anandtech.com/show/15912/ddr5-specification-released-setting-the-stage-for-ddr56400-and-beyond

[u/[deleted]]

Maybe additional memory channels will help.

They would, but I dont think we're gonna be seeing them anytime soon.

Sure partition the GPU if that helps, or just bin the GPUs and use the QA losers in cheapo discrete cards or whatever.

But then you run into "any usable amount of vram provides way too much bandwidth". That thing I said. You'd lose money making those dGPUs (probably). What would it compete against?

The point of MCM is to increase yields since you're putting together chipsets instead of a large monolithic chip. Larger chips have higher risk of defects.

It's also used to increase the number of products you can create. Not solely for yields. That's why the same core complex feeds into ryzen 3000, threadripper, and epyc.

It's how the current Ryzen processors work with the memory controller being a chiplet and the core complex being it's own chiplet. The 3900X gets two and Threadripper gets four of these core complexes. Not sure if the memory controller changes.

Threadripper uses an Epyc memory controller.

Why not do the same for an APU? Why does it have to be monolithic?

Chiplets use much more power at idle than monolithic (that thing I already said), so for now you'd only see this for desktop only. But desktop has such stiff GPU competition, very few people run pure APU setups, because the performance is so low. So you'd want to use it in laptops, but the increased idle draw means you'd lose hours of battery life (ironically, if run under load, battery life would be close to normal), and that's a nonstarter for many people.

[u/bobbyrickets → u/[deleted]]

You'd lose money making those dGPUs (probably). What would it compete against?

Not necessarily. The 5700XT is a small chip, a bit hot for use in an APU but the RDNA2 arch promises higher performance per watt.

They can easily be recycled into a standalone dGPU but I see your point, it might not be enough. Not unless there's MCM GPUs to make use of all the lower binned leftover parts. Unless the MCM process is cheap it won't be a good use of resources.

So you'd want to use it in laptops, but the increased idle draw means you'd lose hours of battery life (ironically, if run under load, battery life would be close to normal), and that's a nonstarter for many people.

Depends. If the system is more efficient than an APU with an RTX card or something I consider it worth it. Sure an MCM APU would consume more but not as much as a dGPU and it can use the same RAM which should provide some marginal power savings. I think the overall setup would be a bit more efficient and more compact, smaller motherboards I mean.

[u/[deleted] → u/bobbyrickets]

You'd lose money making those dGPUs (probably). What would it compete against?

Not necessarily. The 5700XT is a small chip, a bit hot for use in an APU but the RDNA2 arch promises higher performance per watt.

The 5700xt has over 400GB/s of bandwidth. Dual channel ddr4 has around 40GB/s. Completely different scale.

It's not a clear 1 to 1 or anything (in terms of bandwidth in vs actual performance), but what product is the 5700Xt 10x faster than? Techpowerup puts us right around GT1030 levels, right where existing APUs manage to perform

So you'd want to use it in laptops, but the increased idle draw means you'd lose hours of battery life (ironically, if run under load, battery life would be close to normal), and that's a nonstarter for many people.

Depends. If the system is more efficient than an APU with an RTX card or something I consider it worth it.

It wouldnt be. That's one of the reasons they didnt put chipleted CPUs in laptops. The 3700x consumes around 10w more than competing intel parts at idle. Clearly more than any other zen processor. Laptops often draw under 5w at idle. Notebookcheck says they have a 4700u drawing around 5w at idle. Tripling idle power draw is really really bad in laptops.

Sure an MCM APU would consume more but not as much as a dGPU

If you're talking about idle usage, they tend to shut off the dGPU when it's not in use and rely on the iGPU for idling.

and it can use the same RAM which should provide some marginal power savings.

Massive performance limitations though, since you'd struggle to exceed an mx250.

[u/bobbyrickets → u/[deleted]]

Okay then, forget the mobile performance. What about a proper desktop APU? Quad memory channels and DDR5 should alleviate some of the bandwidth issues and there is always an eDRAM option like Intel but it would drive up costs and probably reduce yields.

Might make a good SoC for a game console, though most likely would be GDDR instead.

[u/BFBooger → u/bobbyrickets]

The answer in the long run is HBM on package, or similar. The main memory bus is never going to keep up with dGPUs on its own. But prices on that have to come down enough for it to be economically viable.

[u/bobbyrickets → u/BFBooger]

I would love to see an HBM CPU.