Three AMD Ryzen 9 7950X3D misconceptions debunked

AMD’s new V-Cache-infused AMD Ryzen 9 7950X3D and 7900X3D processors are now formally on sale, creating the company’s “best of both worlds” design confusion.

Both Ryzen 9 X3D chips ship with two dies inside. One die is stacked with a V-cache on top to speed up gaming, while the other non-cache-contained die can hit higher clock speeds. AMD said it made this decision — rather than having both die with V-cache — because many applications don’t care about the extra 64MB of cache and instead benefit from the higher clock speeds.

Unfortunately, we’ve seen a lot of misconceptions about AMD’s approach on the Internet, with some enthusiasts outright calling the CPU a “scam,” and others wishing the 12-core 7900X3D could be built on what the company called Never done before. , In the interest of spreading good information instead of bad, we’re clearing up some of the misconceptions we’re seeing.

Further reading: Ryzen 7950X3D review: AMD’s monster gaming CPU also acts like a pro

Ryzen 9 7950X3D’s second death is “incompetent” or “scam”

A common misconception we see often relates to how AMD Ryzen is managing where applications run on their dual-die approach. These allege that Second Dice is “inefficient,” “a scam,” and that you can’t access it while gaming—effectively turning your 16-core CPU into an 8-core CPU. This simply is not true.

Without access to fancy thread director technology similar to Intel’s implementation in 12th and 13th generation Core chips, AMD relies largely on the operating system being able to identify games. Once a game is recognized as the focused application in the foreground, the system tells the second die to “park”. Parking does not Meaning permanently turned off or disabled, as it was with AMD’s original Threadripper. That CPU actually powered off a die, which could only be turned back on after a reboot.

With the Ryzen 9 7950X3D, parking the second die basically redirects all of the game’s threads to the first die, keeping all of the game’s threads on the cached or stacked die. In our experience, it’s a very blunt tool and everything is whacked when the die is under a certain threshold.

However, that doesn’t mean the second dice is “disabled”. Think of it more as a standby if there really is work to be done.

For example, we played a game with Google Chrome in the foreground running a benchmark (a very lightly-threaded task) as well as Cinebench R23 running on four threads, then switched back to the game. Much of the game as well as Google Chrome and Cinebench will mostly stay on the Stacked Die’s 16 available threads.

We then tasked the Cinebench R23 to run 16 threads—in addition to the game in the foreground and Google Chrome running a benchmark—consuming the core’s full die. Under this condition, both dies would be awake and functioning, even if a game was in progress.

So no, Internet, you’re not “cheating” with that second core.

Ryzen 9 7900X3D will feature an 8-core die and a 4-core die!

Adam Patrick Murray / IDG

We’re not sure where this rumor started, but it’s continued to bubble up in recent weeks as the Ryzen X3D launch approaches. Despite the fact that AMD hasn’t built an 8+4 chip into any of its 12-core Ryzen chips, somehow there’s been a persistent whisper that the 12-core 7900X3D is a combination of 8-core and 4-core designs. will use

According to AMD Ryzen this is not true. As expected, the design for the Ryzen 9 7900X3D will feature the expected 6-core plus 6-core design as the previous ones have, one of which is stacked with V-cache. So why wishcasting for 8+4? We suspect there’s some hope that the chip will move towards giving CPUs the advantage of a full 8-core die that would benefit from being “only” a 6-core CCD with V-cache.

And yes internet, the Ryzen 7 7800X3D will also have a single 8-core design – not a 4+4 dual-core design as some have also floated.

The Ryzen 9 7950X3D similarly needs a “huge check list” to work with.

IDG

This last misconception is based largely on a document provided to reviewers (and we suspect software and hardware developers) to make sure their dual-die Ryzen 7000 X3D systems were working correctly. The document provides 47 pages of step-by-step instructions. Some took this to mean that users may have to take similar steps for full functionality. According to AMD this is not true. The company says that all consumers need to do is make sure the BIOS is updated to the latest (which adds support for the Ryzen 7000 X3D parts) and load the latest available Ryzen drivers. The third step would be to make sure the Microsoft Xbox Game Bar is updated via the Windows Store, as it is in charge of assigning games to V-Cache equipped dice.

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put down your pitchforks

Despite these misgivings, there are certainly still many open questions about AMD Ryzen  7000 X3D chips going forward.

Obviously, this is a different way of building a CPU than what we’ve seen before. Could AMD have benefited from less confusion, or relied on the operating system to do the heavy lifting, such as Intel’s thread director approach? Perhaps. Taking a longer-term view, it also becomes clear that processor companies mix different chips with different performance capabilities, managing how the OS and less sophisticated games and applications use those assets. , it’s also going to be increasingly important.

For now, AMD’s approach “mostly” works. We found in our testing that it gives us expected high boost clocks on par with the Ryzen 9 7950X under light loads, slightly lower performance under all-core loads (due to its slightly lower clock speed), and Very Impressive gaming benefits where cash matters. But there were times when we wished we could assign some game to a non-stacked die, instead of just pushing all the games to the stacked die.