AMD Zen 4c Not an E-core, 35% Smaller than Zen 4, but with Identical IPC

[Aquinus]

I'm pretty sure that I know what "c" stands for.

 

[A Computer Guy]

“c” for “cloud”. Gotta get the buzzwords in.

Oh geez. I hope they are not moving to a core subscription model. Renew online now before your cores are deactivated!

 

[dragontamer5788]

I'm pretty sure that I know what "c" stands for.

Your meme is good enough for me.

 

[Dr. Dro]

That will depend on the application, I think. In non-gaming workloads, I expect this to be just as good as regular Zen 4.

It will. This isn't entirely a new concept, with Intel Wolfdale processors the only difference between the Celeron, Pentium and Core 2 Duo-branded parts was the amount of L2 cache enabled. The Celeron parts had 1 MB, Pentium 2 MB, Core 2 Duo E7000-series 3 MB and the Core 2 Duo E8000-series had 6 MB. On these, the cache size dictated the chip's performance to the absolute extreme, but it also meant that in workloads which were entirely insensitive to cache, the Celeron would perform practically just as great as an E8000-class processor. As an additional segmentation measure, Intel disabled SSE4.1 support on the lower range (non-Core 2 brand) CPUs, but I have a distinct memory of running PCSX2 quite well on the Celeron E3200 in SSSE3 mode back then.

Of course, the emulator was completely different to the one we have today, so you won't have the same success replicating that with a modern build of PCSX2. I suppose we shouldn't expect to see Zen 4c adopted on desktop, but you may see it in low-power, cost-efficient mobile SoCs eventually (such as a Mendocino/Zen 2 ULV replacement).

 

[Oberon]

Cache is actually pretty energy heavy and can be one of the hotter parts of the chip.

Do you have any examples where this is the case? Here's my 5900X running small FFTs on all cores:

Despite taking approximate equal amounts of die space, the L3 temps are approximately 30% lower (indicating proportionally lower power consumption.) There are probably benchmarks of chips with v-cache out there against chips without it running at the same clocks and core voltages that would show minimal differences between the two, but I'm too lazy to look. We could also just look at the stock performance results of the 5800X3D and see that, despite having approximately 30% more silicon due to the slice of v-cache, it actually consumes considerably less power than the 5800X while only running at a 100-200 MHz deficit.

 

[R-T-B]

Do you have any examples where this is the case?

Not in Ryzen. Most of my examples are antiquated. I was corrected above.

 

[Mussels]

Should've gone with zen 4l for lite or something, why the heck did they think 4c was better?

c is for compact
"lite" implies less performance - these are designed to be 100% the same performance, in memory intensive tasks where the cache doesnt help



It's very clear their goal is to have balanced CPU's, but then CPU's with a mix of 3D and C cores - 8 3D cores will provide top-tier gaming performance, while they can suddenly fit more C-cores in the same space (which makes them cheaper to produce) and have an 83D+12C setup out fairly easily with their chiplet designs

Do you have any examples where this is the case? Here's my 5900X running small FFTs on all cores:
View attachment 301360
Despite taking approximate equal amounts of die space, the L3 temps are approximately 30% lower (indicating proportionally lower power consumption.) There are probably benchmarks of chips with v-cache out there against chips without it running at the same clocks and core voltages that would show minimal differences between the two, but I'm too lazy to look. We could also just look at the stock performance results of the 5800X3D and see that, despite having approximately 30% more silicon due to the slice of v-cache, it actually consumes considerably less power than the 5800X while only running at a 100-200 MHz deficit.

The 5800x3D is the example, where the cache runs hotter and they have to be clocked down
Remember that by the time us home users run a test, we're already running them optimised - we cant run a 5800x3D at 5.05GHz and compare to a boosted 5800x

They managed to find a way to force windows to allow them to match intel with Async CPU designs with their drivers, so now they can get fancy and have 3D, normal and C cores and mix and match a dozen products from 3 parts

 

[Oberon]

The 5800x3D is the example, where the cache runs hotter and they have to be clocked down
Remember that by the time us home users run a test, we're already running them optimised - we cant run a 5800x3D at 5.05GHz and compare to a boosted 5800x

The 5800X3D runs comparably hotter because they're literally insulating the underlying core with a whole other slice of heat-generating silicon on top of it. You can also independently monitor the cache temps on those chips and see that it still runs cooler than the cores.

 

[Mussels]

The 5800X3D runs comparably hotter because they're literally insulating the underlying core with a whole other slice of heat-generating silicon on top of it. You can also independently monitor the cache temps on those chips and see that it still runs cooler than the cores.

Just because its cooler than the cores, doesn't mean it's capable of running as hot as the cores without dying

 

[TechnoLadz]

Intel can pack 4 E-Cores in the same size as 1 P-Core. What about AMD? How many Zen4c cores for one Zen 4 core?

If the E core is 1/4 the size of Intel's P Core, then if we use the presentation from AMD on August 29th 2022, you can see that Golden Cove is 7.46mm^2. Raptor Cove is a refresh of Golden Cove, so let's presume the same size. 7.46/4 =~ 1.87mm^2.

 

[Oberon]

Just because its cooler than the cores, doesn't mean it's capable of running as hot as the cores without dying

Cool story, but 1) the limitation on the v-cache parts is a voltage issue rather than a temperature issue and 2) that has almost nothing to do with the point we were discussing.

 

[Mussels]

Cool story, but 1) the limitation on the v-cache parts is a voltage issue rather than a temperature issue and 2) that has almost nothing to do with the point we were discussing.

I can't help it that people are talking about different things
Voltage does nothing, it's amps that's the problem - and the problem is the heat from high amps kills the 3Dcache, at lower temps than the CPU's can safely run at

 

[AusWolf]

I can't help it that people are talking about different things
Voltage does nothing, it's amps that's the problem - and the problem is the heat from high amps kills the 3Dcache, at lower temps than the CPU's can safely run at

That should be fixed in recent BIOSes... "Should"...

 

[Oberon]

I can't help it that people are talking about different things
Voltage does nothing, it's amps that's the problem - and the problem is the heat from high amps kills the 3Dcache, at lower temps than the CPU's can safely run at

[citation needed]

 

[dragontamer5788]

x3d cache is SRAM, right? Which means its RAM created with NAND-gates, very similar to logic (aka: the kind of silicon used in the core for add/subtract/multiply circuits).

That would mean that I expect it to have similar heat/power/thermal constraints as any other logic-chip. Because SRAM IS logic.

 

[AnotherReader]

x3d cache is SRAM, right? Which means its RAM created with NAND-gates, very similar to logic (aka: the kind of silicon used in the core for add/subtract/multiply circuits).

That would mean that I expect it to have similar heat/power/thermal constraints as any other logic-chip. Because SRAM IS logic.

But unlike logic, SRAM is only activated a few gates at a time. So power consumption is much lower than you would think. Moreover, in modern chips, getting the data is the most power intensive part. The constraints of 20 years ago aren't relevant. Execution units are cheap; wires are expensive.

 

[Mussels]

[citation needed]

google is your friend, i'm not here to hold your hand and provide links for every single thing you've never heard of

 

[R0H1T]

Well AMD's just released their first quad core desktop chip in 4(3?) years

AMD Quietly Introduces Ryzen 3 5100 Quad-Core Processor For AM4

 

[InVasMani]

google is your friend, i'm not here to hold your hand and provide links for every single thing you've never heard of

source?

 

[Deleted member 232534]

AMD vp said about those cores in the interview

So mobile, laptops?
I think laptops are a far more practical application for where you might see that adopted much more quickly.

TPU Interviews AMD Vice President: Ryzen AI, X3D, Zen 4 Future Strategy and More

In this exclusive interview, we talk to the AMD Vice President who's responsible for AMD processors, both on desktop and mobile. Of course we had to ask about AI, but we also learned more about AM5 APUs, core counts, chiplets, Hybrid Architectures, Zen 5 and Intel's x86s proposal.

www.techpowerup.com

 

[Mussels]

Well AMD's just released their first quad core desktop chip in 4(3?) years

AMD Quietly Introduces Ryzen 3 5100 Quad-Core Processor For AM4

Brain fart
AM4!

I mean, i said new CPU's were coming to AM4 a while back but this isn't what i had in mind.

My guess is AM4 is their budget platform now - they want to keep selling A520 and B550 boards (and the chipsets) with some AM4 CPUs to the low end market, while AM5 matures and gets cheaper over time

It makes sense for them to sell one generation old + the new at the same time, so they can keep two production lines running at any given time.
That way their budget stuff isn't fighting for fab space of the high end parts

 

[A Computer Guy]

Brain fart
AM4!

I mean, i said new CPU's were coming to AM4 a while back but this isn't what i had in mind.

My guess is AM4 is their budget platform now - they want to keep selling A520 and B550 boards (and the chipsets) with some AM4 CPUs to the low end market, while AM5 matures and gets cheaper over time

Based on the trend I've seen with the prices of 1000, 2000, 3000 chips I suspect once 8000 series is released the 5000 series chips won't be as cost effective anymore and the 7000 series will move into that spot for better price for performance dollar.

 

[Deleted member 232534]

 

[Mussels]

Based on the trend I've seen with the prices of 1000, 2000, 3000 chips I suspect once 8000 series is released the 5000 series chips won't be as cost effective anymore and the 7000 series will move into that spot for better price for performance dollar.

Once they shrink to a smaller node for the performance parts, they can keep using the larger process and taper off the oldest one
it spreads the risk out, and lets them get more products to market against all those seemingly random launch shortages we've suffered


That video explains what's been niggling in my mind with intels un-Efficiency cores: The AMD cores are using 1.5-2W each on those 96-128 core chips. Those arent even the new C cores.

~100W to 6 3D gaming P cores and 35W over 16 C cores?
Yeah, that would work wonders. Imagine office PC's and laptops at that power level, if they arent boosting them out of their efficiency curves.

 

[londiste]

That video explains what's been niggling in my mind with intels un-Efficiency cores: The AMD cores are using 1.5-2W each on those 96-128 core chips. Those arent even the new C cores.

~100W to 6 3D gaming P cores and 35W over 16 C cores?
Yeah, that would work wonders. Imagine office PC's and laptops at that power level, if they arent boosting them out of their efficiency curves.

Epycs are running this stuff at 2-3GHz. Limiting a desktop (or laptop) CPU to that has a pretty profound effect on any load that is single-core or depends on few cores. Games are the obvious practical example - some will work just fine with a minor performance hit but in general you'd take a sizeable one. Benchmark results for anything like that - maybe Cinebench - would also be quite devastating.

It is a bit of neverending conundrum with chips - desired optimization points. As a manufacturer, do you want or can you sell efficiency as the main point? CPUs are a little trickier at that but GPUs might be an easier example - would you want an RTX 4090 at 300W power limit? How about 150W? Given that everything that would go into such product remains the same, meaning the cost would also be the same.

There is always possibility of limiting the larger CPU (or GPU) to the desired spot. AMD even has ECO mode. Both AMD and Intel (and Nvidia) have configurable power limits and depending on specific thing and needs also frequency limits. Basically, take a 7800X3D, limit its frequency to 3GHz and set the power limit at 24W and see where it leaves you and whether you would be willing to pay the cost for the results you get. Would be an interesting test, to be honest.