What are Asus PCs ROG Zephyrus G14, G15 and TUF 566IV all have in common? They are equipped with AMD Ryzen 4000H processors, code name Renoir, and an Nvidia GTX 16 or RTX 20 graphics card depending on the references. At best, it’s an RTX 2060 Super (Max-Q or classic) which is responsible for displaying the textures on the Full HD screen (rarely 4K).
Don’t get me wrong, it’s a good 3D chip, well suited for Full HD gaming and capable of running a lot of titles. And his arsenal of talents also allows him to display a whole bunch of graphic effects like the famous ray tracing, one of the new fads of the video game industry.
A question of performance-price ratio?
An RTX 2060, that’s it. You may skim the catalog of Asus but also other brands versed in the art of creating gaming machines, you will not find a PC with a Ryzen 4000H and an RTX 2070, for example. Why ? We resumed the long technical presentation to which AMD invited us at the launch. Nothing, and yet there was material!
We put the question to some of our contacts with PC manufacturers but none were able to justify this fact to us other than by a purely commercial argument, price positioning or performance-equipment-price ratio.
White cabbage also to find an answer or a technical diagram on the AMD site. The only information relating to PCI-Express which can be found on the processor data sheets is the version as shown in the image below.
However, it seems that these arguments and these fruitless searches did not dampen the desire to understand of the journalist and owner of the site Igor’s Lab.
He used a good number of his connections, to such an extent that he managed to obtain several confidential technical documents that he hastened to analyze, comment on and publish and which provided us with an answer to our question.
AMD Ryzen 4000H: from processors to small pipes
As is often the case in IT, it is the information circulation channels that are the source of this situation.
According to the diagram below, the Renoir SoCs – or AMD Ryzen 5, 7 and 9 for laptops – do indeed use the PCI-Express 3.0 protocol to communicate with the graphics card, as has been the practice for a while and in happening to change, with the arrival of PCI-Express 4.0.
But they’re not using it at its full speed. Instead of communicating in 16x with the GPU as is the custom, the Ryzen CPU can only communicate at 8x maximum, 4x minimum. This is what the first indication explicitly shows, starting from the top, on the right column.
A speed which is, according to several specialists, including our colleague, sufficient to manage the data rates exchanged between the CPU and an RTX 2060 Super GPU … but which would be a real limit if an RTX 2080 were associated with a Ryzen 9 4900H, for example. The exchange pipe would be very quickly cluttered or even saturated, which would cause quite annoying performance drops and very unhappy players.
After testing the three Asus laptops mentioned in the introduction, all equipped with Ryzen 4000H and RTX 2060, we have to admit that the chemistry works perfectly. The performances are there, the greedy and recently released games turned out to be playable in very good conditions. They are well-balanced platforms, fun to use for gaming and everything in between, and their price is, all in all, reasonable.
A justified limitation that should have been explained
Why was AMD forced to resort to such a limitation? The consumer argument is the first viable hypothesis. AMD arguably had to compromise on many levels to prevent Ryzen laptop chips from turning into true watt-hungry ogres.
It was necessary to design a powerful, efficient, not too energy-consuming and affordable chip in order to reconquer the market for portable PCs for gamers, a market in which AMD had been conspicuous by its absence for ages.
Technically now, if your processor architecture offers multiple transfer channels and they are all running at full capacity, the cores will use them. And therefore need energy to pass the information processed or to be processed.
By side effect, having large, very fast supply channels will therefore encourage an increase in the consumption of the chip. And who says sustained activity, says calories, which brings us to our second hypothesis of reflection: thermal stress.
A laptop PC is, by definition, more difficult to cool than a desktop PC since internal space is more limited. The dissipation devices are therefore designed for the best and very often embody small masterpieces of engineering.
To prevent the heating from being too important, you might as well make sure to limit the category of GPU (mid-range +) that can be associated with a processor which itself sees some of its dimensioned components. at the best.
This choice, well explained, could have been a strong differentiating argument against to Intel solutions (which offers 16x), a good way to justify the very aggressive price of machines and, above all, a good way to help the consumer to choose a machine adapted to his needs according to his budget.
It is a bit of a shame that AMD did not play its card on the table from the presentation of the Ryzen 4000H and did not make this speed limit a force rather than ignore it and have it appear, now , as a weakness or a desire to cheat the end consumer.
Source: Igor’s LAB