Testing The World’s Best APUs: Desktop AMD Ryzen 4750G, 4650G and 4350G

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There are two very important levels of graphics performance in modern systems to consider – one is if the graphics system is sufficient for seamless use, and the second is such that it meets a substantial standard for gaming. On one side we use integrated graphics, which take advantage of a unified processor to simplify the system, and on the other we look to a range of options, such as smartphones, consoles, and discrete graphics options. Somewhere in there we have a middle ground – can an integrated option have enough thermal headroom and graphics power to worthwhile for gaming? This is the pitch of AMD’s Ryzen 4000 based APUs, which combine Zen 2 CPU cores with fast Vega 8 graphics. With a 65W headroom, it should surpass anything that mobile processors have to offer, but is it enough to replace the low-end discrete graphics market?

When a CPU meets GPU

AMD is the company of the accelerated processing unit, or APU. The company introduced the term in 2011 when it started combining its x86 CPU cores and some form of graphics accelerator into the same piece of silicon. This combined processor, built for the laptop and desktop market , was designed to remove the need for a completely separate graphics card in a system, simplifying the design and bringing down overall cost for anyone that simply needed a graphics output for simple tasks. At the time, these solutions were very much for the low-end market.

Combining a CPU and a GPU on the same piece of silicon has a variety of tradeoffs involved. The key benefit is reducing that bill of materials, but there are also advantages in the latency of communication between the CPU cores and the GPU acceleration as the data does not need to go off the chip. There can also be benefits in power control, with a system being able to manipulate how much power goes to each in a simpler way.

But there are a number of downsides. The total power consumption of the system now gets condensed into one thing, rather than split across two. This makes the one APU a central hotspot for cooling support. Also, adding in graphics will make the single CPU die size larger, making it more difficult to yield compared to two separate pieces of silicon. It can also be complex if both CPU and GPU have to be made on the same manufacturing process, depending on the initial design for those architectures. There is also the memory problem – graphics loves memory bandwidth, and CPU memory controllers are slow by comparison; while a GPU might love 300 GB/s from some GDDR memory, a CPU with two channels of DDR4-3200 will only have 51.2 GB/s. Also, that memory bank needs to be shared between CPU and GPU, making it all the more complex.

For ultra-mobile laptops, the tradeoff in having a single combined APU is worth it, as it also means there can be a bigger battery and reducing the number of items inside the shell helps with aesthetics and thermals. Also, ultra-mobile laptop users are not often demanding super graphics performance for 4K gaming, and so something that provides ‘enough’ performance, at a suitably low power, is often preferred.

The higher the performance that a combined CPU+GPU piece of silicon, this arguably also reduces the market for graphics by taking away options at the low-end. If a simple APU can perform graphics duties of a $100 graphics card, then there is arguably no need for $100 graphics cards any more. We can compare what each GPU vendor has launched in the last few years for the ‘entry gaming market’ to confirm that the market below $100 is now for APUs and simple ‘must-have-a-screen’ cards for the pre-built market.

Perhaps surprisingly over the last couple of years, despite at one point AMD promoting its RX 480 card as a possible $200 gaming card, both companies are veering heavily towards the high-end gaming market, leaving the budget range for OEMs, and arguably also the mid-range as well. Both AMD and NVIDIA with the latest releases start at a relatively hefty $399 MSRP, which is a world away from the $200 suggested low-end price for the AMD RX 480 at launch. Part of this is driven by new gaming features like Ray Tracing, the fact that leading edge graphics tend to launch at the high-end first, as that is where the biggest return on investment is, and with the rise of high resolution gaming, 8 GB of video memory seems to be the new minimum, if not more, which drives up the total cost.

So if APUs are there to bridge the gap, then we’re at a bit of a quandary. Intel has leading edge integrated graphics solutions with its latest Xe-LP Tiger Lake processors, however these are for mobile use only. In that market segment, a good performing chip has a better financial return than the same silicon used in a desktop socketable processor, and with Intel looking to drive mobile volume it is putting all that silicon for mobile use right now.

This means that the only company taking socketed desktop graphics seriously right now is AMD, who is starting to use its mobile-first Renoir silicon for desktop processors. This involves moving the TDP from 15W/45W up to 65W, and putting it in an AM4 socket package, similar to what AMD has done with its previous APU silicon. But now we get onto a specific issue with AMD’s Ryzen 4000 desktop APUs.

Ryzen 4000 Desktop APUs: Not for General Sale

That’s correct – the Ryzen 4000 desktop APUs from AMD are not available at retail. While AMD announced twelve different model numbers for the latest generation, varying in core count, graphics count, and power, the company has decided not to create special retail packaging and offer them for general consumption.

What AMD has done here is enable these products for two specific markets. Companies like HP, Dell and Lenovo can order these processors from AMD and put them into pre-built systems for consumers like you and I, or they can order the Ryzen PRO versions and build commercial systems with extra management features for corporate management.

By enabling these processors only in pre-built and commercial systems, this allows AMD to have a tighter control on its stock of processors. These companies purchase processors on the scale of tens of thousands, so if a big OEM like HP wants to create a series of pre-built computers, they can put the order in with AMD and AMD will give HP a delivery date. If a product is sold on the open market, then AMD has to work with distribution channels dealing with a scale of tens of units, rather than thousands, making the operation more complex with stock potentially either sitting idle, or not being available if they cannot manufacture enough.

By keeping this hardware as OEM only, AMD can adjust its silicon between desktop and mobile as required with much tighter controls. This is important for a company if the same product in one market (e.g. this silicon in mobile) is worth more than the other, as it focuses the silicon in the mobile market while also meeting contractual demands on the desktop side. Reports of AMD needing more 7nm wafers from TSMC could also play into this, as AMD would rather use those wafers for higher margin products.
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