A practical take on Steam Deck performance (but really just general observations intended for Reddit hype)

FlippantGod
Mon, 19 Jul 2021 23:28:57 +0000

Edit: Formatting by the generous PetitPrince.

Steam Deck | AMD Ryzen 7 4800U
7nm TSMC process | 7nm TSMC process
AMD Zen 2 CPU | AMD Zen 2 CPU
4 cores / 8 threads | 8 cores / 16 threads
2.4GHz base clock / 3.5GHz turbo | 1.8GHz base clock / 4.2GHz turbo
unspecified L3 cache (4~8 MB) | 8 MB L3 cache
AMD RDNA 2 GPU | AMD Radeon RX Vega 8
8 CUs | 8 CUs
1-1.6GHz | up to 1.75GHz
4-15 Watts | 15 Watts (10-25W and up to ~48 total system in some laptop benchmarks)
16GB LPDDR5 5500MHz | LPDDR4 4266MHz
128-bit memory bus width (32-bit quad channel) † | 64-bit memory bus width (32-bit dual channel)
40Whr battery (2-8 hrs gameplay) †† | /

† shared between CPU and GPU; exact memory access scheme unspecified
†† ~2.5 hrs at rated 15W APU power draw; also consider SSD, screen, controls, WiFi, etc.

7nm process

This APU is probably on the exact same TSMC process node as the Ryzen 7 4800U.

CPU cores

Half the cores; worse multithreading performance. More power for the GPU†.

† power management features probably do this in practice.

Overall this shouldn't matter much. Maybe impacts people who compress game files or want to use the Steam Deck for things other than gaming.

CPU clock speeds

A somewhat low max boost. Probably from power and thermal considerations. Is it the sustained max boost? With just the CPU? How about max GPU? Can it clock higher when docked?

A surprisingly high minimum clock. I hope it can clock lower than 2.4GHz.

Overall, this is subject to power and thermal limitations and management. Needs to be tested by a trusted third party. I am hopeful that as a handheld PC, we can adjust clocks and boosting behavior. These behaviors may be different on Linux compared to Windows.

CPU cache

Unspecified, I expect 8MB from AMD but we could see 4-6 as a cost and power saving measure.

GPU

Docked performance will likely be held back by the 8 CUs.

The clock speeds look good, about what was expected. Same goes for sustained boost as for the CPU boost.

By implementing the Radeon RX Vega 8 on 7nm, the process improvement gains have already been realized. Additionally, I speculate that AMD has had ample opportunity for some under the hood improvements to the aging microarchitecture. Some benchmarks found it to be 30-40% faster than an RX Vega 10 (a larger GPU) on the older process node. However, the clock speeds were twice as high compared to the RX Vega 10. Consider also that the 15W laptop was pulling ~48 watts.

Since it becomes difficult for me to speculate on GPU microarchitectural improvements, I will consider the APU's 8 CU RDNA 2 GPU to have comparable performance to the Ryzen 7 4800U's Radeon RX Vega 8.

This is mostly for convenience. It may be realistic to expect somewhat lower performance because the handheld Steam Deck APU is unlikely to be allowed to pull more than 20~25 watts. More on this in the battery life section.

By far the most significant improvements from the RDNA 2 GPU, in my mind, stem from the latest GPU features; modern video decoding, Vulkan features, mesh shading, and more. Also, being the same microarchitecture that console developers will be targeting.

Feel free to substitute your own speculative performance, but please don't let hype bias your expectations, and be careful when seeking out benchmarks.

APU power draw

4 watts is pretty clearly the minimum idling draw seen in windows laptops with Zen 2 CPUs.

Unfortunately this is high compared to ARM CPUs. It may also be subject to the level of optimizations done on the firmware and the custom Linux distribution. People willing to roll their own might be able to get this lower? It would require getting your hands dirty, and don't bank on it. I'll be happy if Valve actually gets idling consistently down to 4 watts.

As for 15 watts, it is pretty clear that commonly shared expectations of the hardware are not tailored for this rated power draw. People are expecting performance that comes with 40-80 watts. I expect the APU to draw as high as 20~25 watts in certain circumstances, but this is speculation, and cannot be verified until Steam Decks are in the hands of trusted third party reviewers such as Gamer's Nexus.

And make no mistake, drawing anything over 15 watts in the APU will have battery life implications, which I will cover later.

RAM

If there is anything I am allowing to build my expectations, it is probably this. To my knowledge, we haven't much seen LPDDR5 in devices yet, so there is some novelty and some unknowns.

Compared to DDR4/LPDDR4, even this reduced speed (saving more power btw) LPDDR5 memory will be faster, finally reaching something similar to dedicated GDDR memory speeds on older budget discrete mobile graphics cards. It has plenty of new power saving features, and should generally draw less power anyway.

But let me be clear on what it isn't; it is not GDDR5, and it is not GDDR6 as seen in the Xbox Series X or S. Please do not confuse these. I have seen people refer to it as all kinds of things. IT IS NOT GDDR, IT IS NOT LPDDR4, IT IS NOT LPDDR6.

Okay. With that out of the way, the other half of this that has me tentatively hopeful is the listed 128-bit quad channel memory. I am not qualified to speak on the nature of memory accesses and on memory channels, but generally, this should be responsible for the memory bus bandwidth to approach that of budget discrete graphics cards.

Hopefully this improves the GPU performance significantly.

Also, while I initially assumed 16 GB of RAM was such overkill for the target resolutions that it could only be to pander to the PC gaming crowd which would identify the gratuitous RAM with a premium product, I speculate it was just a byproduct of having four memory packages for quad channel. I'm guessing the smallest packages LPDDR5 came in was 4 GB. Anyway, I might be wrong on this account, and it doesn't much matter; there is more than enough RAM, faster I believe than any older APU already on the market (we aren't counting the consoles okay), and it should save power all the while.

Considering people would still be buying the Steam Deck regardless, I say well done Valve, even if it was required to hit performance targets or actually a financial boon behind the curtain.

Storage

At first I was upset the base model was eMMC rather than an NVMe SSD, given how cheap 64/128 GB SSDs are in bulk. On second consideration, it makes a lot of sense.

I speculate that at best, the base model has an extremely narrow profit margin. Even a cheap SSD might eat into that. But even more, eMMC should be more than enough for anyone intending to use the Steam Deck primarily for 2D games and emulation, which is historically a staple segment of the handheld market. These are the games that will also be happy on a microSD.

In this way, there is some product segmentation for the mid and high tier models, which are making money on the storage.

I personally have placed a reservation for the base model, although I intend to upgrade the storage myself. However, it is difficult to obtain benchmarks of power draw for m.2 SSDs of this size beyond "less than bigger NVMe drives because fewer chips and no DDR4 cache probably", so it might not be an advisable tradeoff to anyone but the budget conscious and those seeking a full 1TB fast NVMe storage.

Speaking of power, my limited findings are suggesting ~3.5W power draw from appropriate m.2 NVMe SSDs, meaning the eMMC model may also deliver the best battery life (even before accounting for less demanding titles). That is probably the listed 8 hours.

Keep in mind I don't know much about the power draw of eMMC, and the power management differences between eMMC and NVMe.

One last thing; Microsoft promised optimized games for the Series S that would have reduced asset sizes for the reduced storage. A promise it appears they haven't been able to deliver on. However, this is a very good idea and I would be THRILLED if Valve was able to wrangle a user selection of asset quality when downloading games. Some PC games have higher quality assets as DLC, and generally as a handheld PC we have some ability to do this manually. Compressing game files might also be an avenue?

Battery life

Everyone looks for different things in a product. So far I've tried to provide a relatively practical, unbiased take on the Steam Deck's listed specs, leaving it up to readers to decide what they care about.

But if you saw the Steam Deck and a short battery life never once crossed your mind, it probably isn't a concern for you. I don't know what your usecase is; maybe permanently docked, perhaps just keeping it around the house. It doesn't really matter, and I think the Steam Deck is a particularly solid value for you in particular.

It is pretty easy to do a battery life calculation. So everyone should do so with their own speculations on the total system power draw, when gaming, idling, etc. Things to account for are the APU, screen, WiFi, SSD, RAM, and so on.

I figure something like 1.5 < x < 2.5 hours for full fat gaming. I probably should have watched the video (holy cow can you believe I'm going to post this whole essay without watching the video!?) but I believe 6 hours 30 fps was thrown around, so that should be the upper limit possible for general gaming and optimized titles. I'm pretty confident the 8 hours is a best case scenario only on the eMMC model running 2D or generally less demanding games.

The math here is simple so make up your own mind!

Lastly, with a PC we have some wiggle room to optimize settings and we can also destroy battery life I'm sure. So remember, frame limits are your friend on a 60 hz screen, and on mobile devices in general. Also, reducing settings possibly. It really goes against my nature as a PC gamer though, considering I play Skyrim with an ENB on a GTX 660M. At a stuttery 10~15 fps. Yeah, sometimes a stable 30 fps is the way to go, but I'm a hypocrite who just can't wait to run 1080p and downscale to remove jaggies!

Weight

I wasn't sure if I should include this, as I am skipping other things like the microSD card slot (other than that I genuinely would have preferred a regular SD card slot so I could emulate having game cartridges; actually, I need to look up splitting game files across onboard and removable storage).

Still, it deserves a mention; I have no clue if it will be too heavy for me. I suspect going from the Switch to the Steck will be frustrating, although some have pointed out that the placement of buttons and joysticks will make it easier to rest it while playing. Also I'mma just call it the Steck from now on, my apologies.

Overall, it looks bulky and heavy and might be a pain to tote around. But modding makes this worth it for me personally.

Actual Performance Numbers Please, or APNP

I am now realizing this is way too long, and I'm spiraling out of control; there's no way I can edit all this! How long has it been since I've slept? Did I eat yet today? I will be downvoted to Oblivion for posting something this unwieldy and unreadable!

Oh well. Before I loose consciousness, I pretty much expect 1280x800 30fps on all titles. Doesn't that seem too low? But there are overheads that go into running unoptimized PC ports of games on Linux, and frankly while Proton does great things, I'm mostly familiar with it on a desktop. What is the experience with a power budget? The Radeon RX 8 struggles with 1080p on some titles; will the Steck be able to hit 1080p 30fps on all titles, let alone 60fps?

Anyway, I've made my base expectations. I personally anticipate for 1280x800 60fps for all titles, albiet at a limited battery life, but I don't think we can take it for granted. Docked performance, remains to be seen. 1080p 30fps seems realistic. Basically my clunky 11lb gaming laptop from 2012 with the GTX 660M, but with waaay more RAM and a tenth of the power draw. In a handheld.

Freesync

I don't think the display supports freesync or, as I've seen some people say, Valve would advertise that. Seems strange given the market, and if expertly implemented could potentially let the display downclock way down when appropriate. To tired to check, but possibly could be implemented down the line? That means NOT a feature, unless it is on the box when you are paying BTW.

Wow, I Can't Believe FlippantGod Won't Shut Up

The price is right, folks, but please don't pretend that this will double as a serious VR rig. That isn't the sort of thing you speculate on before a console is even released and benchmarked by trusted third parties.

What do y'all think of my expectations? Too low? Too high? Any interesting morsels I may have missed? And lastly, will Reddit eat me alive if I post this there? Willing to take any and all criticisms when I wake up! And hey, if someone high up on the Tildes social ladder wants to tag this "Steck", I will forever be in your debt. I am much too scared to do so myself.

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