AMD: Zen 3 Announced [2020-10-08]

Full ISA performance dump: http://users.atw.hu/instlatx64/AuthenticAMD/AuthenticAMD0A20F10_K19_Vermeer_InstLatX64.txt

Surprising to see AMD have invested in the old rusty x87 stack: double rate for FADD and FMUL and single cycle FDIV32. Some legacy math-heavy software will see nice speed bump.
Perhaps a result of having two schedulers and it being easier to duplicate some of the hardware across both?
The server focus may mean some customers may have requested something along those lines.

The way Zen 3 paired up units into dual schedulers is in some ways reminiscent of prior architectures that paired an ALU and AGU. AMD also diagramed instruction dispatch as being its own box, perhaps a new method for dispatch or a pipeline stage? One notable reduction from the prior gen is L3 bandwidth. The bigger cache is shared by 8 cores, but its capabilities look to be the same as a single Zen L3.
 
What are the recommended memory kits for zen3? Reviews say higher Mhz and lower CL is better (obviously) but I cannot find any 3600mhz cl14 kits as some reviewers use. Well, I found one G.skill kit but at ~$700 its more than double a cl16 kit so that is a no-go. If I read correctly the IF is now 2000Mhz so ideally you need a kit that can do 4000Mhz and has low cl? I can't really find anything beyond 3600Mhz cl16 that is somewhat affordable and actually available.
 
I couldn't find any reasonably priced ram either. Locally it went from $300AUD for 32GB G.skill Trident Z neo 3600 CL16-19-19-39 to $450 for the same stuff but 16-16-16-36, which I think is Samsung B die so would also overclock better.

I'm happy to pay 50% more than standard 3200 CL16 ram that comes in at around $200 for 32GB locally but more than that is a rip off... I went for the $300 G.skill 3600 16-19-19-39. Hopefully I either have some luck and can hit 4000MHz at decent timings or it wont end up mattering much.
 
Perhaps a result of having two schedulers and it being easier to duplicate some of the hardware across both?
All Zen architectures were already capable of dual ADD and MUL rates for the SIMD/FMA instructions. With Zen3 and the major re-shuffling of the ALUs plus the additional dispatch ports, I think AMD simply found an opportunity to re-map some x87 instructions on the SIMD bypass network, to take advantage of the existing double rate logic.
One notable reduction from the prior gen is L3 bandwidth. The bigger cache is shared by 8 cores, but its capabilities look to be the same as a single Zen L3.
AMD took the least resistance path with the larger L3 by simply doubling the size of the SRAM banks -- the set associativity and the interface width remained the same. Even the L2 DTLB covers only a quarter of the L3 size. This will be a major point for improvement in Zen4, I think.
 
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What are the recommended memory kits for zen3? Reviews say higher Mhz and lower CL is better (obviously) but I cannot find any 3600mhz cl14 kits as some reviewers use. Well, I found one G.skill kit but at ~$700 its more than double a cl16 kit so that is a no-go. If I read correctly the IF is now 2000Mhz so ideally you need a kit that can do 4000Mhz and has low cl? I can't really find anything beyond 3600Mhz cl16 that is somewhat affordable and actually available.
IF is not 2000 MHz, but good chips can get it that high (our samples haven't gotten there, we maxed out around 1900).
DDR4-3600 CL16 is the "sweet spot" on price/performance. Samsung B-Dies are still the best chips, but others work fine too.

edit: according to AMD future AGESA (supposedly 1.1.0.0 Patch C which some apparently have already?) will improve IF clocking so more chips should be stable at 2000 MHz, but still not all CPUs will get there.
 
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The super low resolution Anandtech benchmarks are insane. In every case even the 6 core Zen 2 is obliterating all other CPU's. We probably need to see games that take full advantage of 16 threads before we get a true picture but based on this it looks like the 5600X might even be faster than the 3700x in very well threaded games. And easily faster in games that don;t take advantage of all 8 cores. It'll be interesting to see how well it holds up against the consoles in real next gen games.
 
Yeah, I was finally browsing through AT review last night while in bed and had a double take when I saw "360p" on some of the charts. :LOL:
 
The 3700x already is a match and then some, that is without thinking of overhead etc.

He's talking about the 5600X being a match for consoles even though it has less cores.

It was a tough decision for me but I went with a 5800X because of consoles having 8 cores (decent ones this time, it didn't count the last two gens) and current games already being fairly well threaded after years of 2 cores being enough.

Unfortunately the 5800X isn't a great value proposition, with the 5900X offering 50% more cores and cache for $100USD more. I couldn't make the stretch though and wasn't comfortable betting on a 6 core not becoming obsolete is 3+ years since this system will be passed onto my wife and will probably be expected to last 6+ years. The 5600X is sure punching above its weight in current games though, so who knows...
 
The difference in SotTR is quite massive between my 3800x and my 5800x

3800X
3800xfiky9.jpg


5800X
5800x_6bjd2.jpg
 
Damn I was hot for a 5800x, but yeah the price diff vs 5900x is around 100euros here (and luckily enough, it's an amount I can spend) ... So I guess 5900x it will be (when stocks are back).
 
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