AUGUST 2019 PCWorld 29crossing between the two clusters of cores
instead of simply dispatching both threads to
the same cluster of CPU cores. That’s now
fixed, and Windows 1903 will send threads
the same cluster of CPU cores when possible.
This, AMD claims, can yield up to a
15-percent boost. Officials also say it’s not
uniform in all applications, however, so your
mileage will vary.
While we used the same amount of DDR4
in dual-channel modes in all three builds, we
did vary one aspect by running the Core
i9-9900K and Ryzen 7 2700X with 16GB of
DDR4/3200 CL14, and the Ryzen 9 3900X
with 16GB of DDR4/3600 CL15. We wanted
to test the Ryzen 9 with its optimal memory
clock, which is 3,600MHz. We intend to test
it at 3,200MHz as well. Due to time
constraints, we’re initially showing only$488: Intel’s mighty Core
i9-9900K. The last chip is none
other than AMD’s $499 Ryzen 9
3900X.
We tested each CPU in
parallel, with the Ryzen 7 2700X
mounted in an MSI X470
Gaming M7 AC, the Core
i9-9900K into an Asus Maximus
XI Hero, and the Ryzen 9 3900X
into an MSI X570 Godlike.
For graphics, the initial CPU
and some game testing were
performed with Founders
Edition GeForce GTX 1080
cards. We ran additional game testing with
Founders Edition GeForce RTX 2080 Ti cards.
All three builds used the latest available
UEFI/BIOS and drivers and fresh installs of
Windows 10 Professional 1903. This version
of Windows is particularly important, because
AMD says 1903 now includes scheduler
optimizations that help it dispatch threads in a
more efficient manner on Ryzen 3000.
Remember: AMD’s CPUs are constructed
with small cities of CPU cores and high-
speed, but slower access between the cities
of CPU cores. In older versions of Windows,
the scheduler would dispatch one thread to a
city in one cluster. Because it was never
designed for multi-die designs, it would send
a second thread to a different cluster of CPU
cores. This would sap some performance, as
the threads would then have to deal with
AMD’s new 12-core Ryzen 9 3900X is the new leader among
mainstream performance CPUs.