Thursday, August 31st 2017
AMD Ryzen Threadripper 1900X Core Configuration Detailed
At its pre-launch media conference call for the Ryzen Threadripper 1900X, AMD mentioned that the chip has been carved out from the common 4-die EPYC MCM using a "4-0-4-0 diagonal configuration," which led to some confusion as to which cores/dies AMD disabled to carve out the $549 8-core HEDT processor. The company shed some light on this matter, responding to questions from TechPowerUp.
It turns out, that the Threadripper 1900X features an entire CCX (quad-core CPU complex) disabled per active die on the multi-chip module, so the CCX that's enabled has 8 MB of L3 cache; and access to the die's entire uncore resources, such as the dual-channel memory controller, PCIe root complex, etc. With two such active "Zeppelin" dies, the Threadripper 1900X ends up with 8 cores, 16 MB of L3 cache, a quad-channel memory interface, and 64 PCIe lanes.
The decision to disable an entire CCX, rather than doing something similar to the "Zeppelin" die as with the Ryzen 5 1400, where both CCX units on the die are enabled with 2 cores, each; and the L3 cache per CCX being chopped down to 4 MB; could be attributed to giving the four cores per active CCX a contiguous block of 8 MB L3 cache, to better cushion the NUMA local mode, in which certain applications' memory access can be localized to one die, for lower latency.
When AMD talks about a "diagonal configuration," it refers to the fact that two out of four 8-core "Zeppelin" dies physically present on the Threadripper multi-chip module, are disabled. The ones disabled are always diagonally opposite to each other. The Threadripper MCM is physically identical to the 32-core EPYC MCM, with four 8-core "Zeppelin" dies under its large integrated heatspreader (IHS); but due to platform-segmentation, and the fact that the Threadripper socket TR4 HEDT platform only has 4 memory channels (unlike 8 channels on the EPYC platform); two dies are completely disabled. The dies are disabled diagonally probably to spread heat better, or for better package wiring.
It turns out, that the Threadripper 1900X features an entire CCX (quad-core CPU complex) disabled per active die on the multi-chip module, so the CCX that's enabled has 8 MB of L3 cache; and access to the die's entire uncore resources, such as the dual-channel memory controller, PCIe root complex, etc. With two such active "Zeppelin" dies, the Threadripper 1900X ends up with 8 cores, 16 MB of L3 cache, a quad-channel memory interface, and 64 PCIe lanes.
When AMD talks about a "diagonal configuration," it refers to the fact that two out of four 8-core "Zeppelin" dies physically present on the Threadripper multi-chip module, are disabled. The ones disabled are always diagonally opposite to each other. The Threadripper MCM is physically identical to the 32-core EPYC MCM, with four 8-core "Zeppelin" dies under its large integrated heatspreader (IHS); but due to platform-segmentation, and the fact that the Threadripper socket TR4 HEDT platform only has 4 memory channels (unlike 8 channels on the EPYC platform); two dies are completely disabled. The dies are disabled diagonally probably to spread heat better, or for better package wiring.
63 Comments on AMD Ryzen Threadripper 1900X Core Configuration Detailed
what a disaster.... basically a died cpu with the 25% of working parts...
nope nope nope
You must be a hoot at parties.
Personally, I avoid castration parties. I know all the cool kids are doing it but it just doesn't sound fun to me.
Time for bed.
Honestly I have an issue with the fact that AMD processors have some difficulty retaining their value with respect to MSRP. So for example, the RyZen 1800X hit the market at ~$499 USD but can now be found for as low as ~$419 and possibly lower.
I don't want to buy a Threadripper 1900X or 1920X at introductory pricing only to find the price lowered by a similar ~16% +/- as the RyZen 1800X.
With Intel the price is the price and you typically don't see price drops beyond a good sale price at Microcenter.
I don't mean to say price drops are bad because they aren't that at all. They just aren't good for early adopters paying introductory pricing.
Edit:
I should note that I might be out this round of Threadripper goodness anyway. While I had tentative plans to buy / build a Threadripper based system I have a family memeber that has a bricked system that they are giving to me. I believe it's a Core i7 5820K or 6800K with GTX 970. I think it just needs a new motherboard but a free Intel 6 core 12 thread processor is difficult to pass up on. So if it all works out I'll defer the the Threadripper build for a few years.
I was therefore mistaken assuming there would be an entry level 10 core 20 thread Threadripper rather then a mainstream overlapping 8 core 16 thread part.
So there is some disappointment there for me but the entry level Threadripper is still a noteworthy part IMO. I'm still not convinced that it won't drop in price like the RyZen 1800X though,.....
1900X = 2x Ryzen 4-core dies
1920X = 2x Ryzen 6-Core dies
1950X = 2x Ryzen 8-Core dies
Probably to make binning dies easier. They aren't testing for 5 and 7 core dies right now, because that would add too much time to the binning process.
And I think the 1900X is a good entry level CPU simply because of the staying power of the sTR4 socket. It is my theory that AMD can enable more than 16 cores if they want, using the extra dies.
Sorry AMD price is not everything.
Jesus we've reached a point where people see lower prices as a bad thing. Also , somehow the fact that Intel maintains their exorbitant prices is a plus. Holy crap...