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AMD Launching 3900XT, 3800XT, and 3600XT Zen 2 Refresh CPUs: Milking Matisse

posted by martyb on Wednesday June 17 2020, @04:31PM   
from the falconry++ dept.

takyon writes:

On July 7, AMD will launch three refreshed Zen 2 "Matisse" desktop CPUs with slightly higher boost clocks than the previous versions:

• 12-core Ryzen 9 3900XT will boost to 4.7 GHz, instead of 4.6 GHz for the 3900X.
• 8-core Ryzen 7 3800XT will boost to 4.7 GHz, instead of 4.5 GHz for the 3800X.
• 6-core Ryzen 5 3600XT will boost to 4.5 GHz, instead of 4.4 GHz for the 3600X.

The 3900XT and 3800XT will not come with a bundled cooler, unlike the 3900X and 3800X (the top-of-the-line 16-core 3950X also did not come with a cooler). 3600XT will come with a Wraith Spire cooler.

The "suggested etailer price" (SEP) is the same as the launch prices for the previous CPUs ($499, $399, $249), but the 3900X is often sold for $400-$420 instead of $500, for example. So customers may end up paying between 10-25% more for a 2-5% potential performance gain, unless retailers drop the prices soon after launch.

The new 3000XT family of processors focuses mostly on boosting the turbo frequency by 100-200 MHz for the same power. AMD states that this is due to using an optimized 7nm manufacturing process. This is likely due to a minor BKM[*] or PDK[**] update that allows TSMC/AMD to tune the process for a better voltage/frequency curve and bin a single CPU slightly higher.

[...] In each [of the] three cases, the XT processors give slightly better frequency than the X units, so we should expect to see an official permanent price drop on the X processors in order to keep everything in line.

The CPUs should work with existing motherboards that supported the non-XT CPUs, after a BIOS update.

A September to October 2020 launch date is likely for the first next-generation Ryzen 4000 Zen 3 "Vermeer" CPUs. Rumors of the launch being pushed back to 2021 have been denied.

[*] BKM: Best-Known Method
[**] PDK: Process Design Kit

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Original Submission

• Re:what's the "ark intel" for amd? (Score: 2) by takyon on Thursday June 18 2020, @06:24PM

  by takyon (881) <takyonNO@SPAMsoylentnews.org> on Thursday June 18 2020, @06:24PM (#1009638) Journal

  There were rumors that Threadripper 3000 would get 8-channel variants, but that never materialized.

  If there is going to be any change for the mainstream Ryzen CPUs, that would come on the new AM5 socket (starting with Zen 4, probably in early 2022), which will use DDR5 memory.

  It's worth noting:

  DDR5 [wikipedia.org] supports a speed of 51.2 GB/s per module and 2 memory channels per module.

  What does that mean? Take it from Rambus: [rambus.com]

  Another major change with DDR5, number four on our list, is a new DIMM channel architecture. DDR4 DIMMs have a 72-bit bus, comprised of 64 data bits plus eight ECC bits. With DDR5, each DIMM will have two channels. Each of these channels will be 40-bits wide: 32 data bits with eight ECC bits. While the data width is the same (64-bits total) having two smaller independent channels improves memory access efficiency. So not only do you get the benefit of the speed bump with DDR5, the benefit of that higher MT/s is amplified by greater efficiency.

  In the DDR5 DIMM architecture, the left and right side of the DIMM, each served by an independent 40-bit wide channel, share the RCD. In DDR4, the RCD provides two output clocks per side. In DDR5, the RCD provides four output clocks per side. The 32-bit data of each 40-bit channel consist of four 8-bit lanes, and each of these lanes gets an independent clock signal from the RCD. Giving each lane an independent clock improves signal integrity, helping to address the lower noise margin issue raised by lowering the VDD (from change #2 above).

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