Why no SMT in Ryzen 3 cpus/apu?

[prtskg]

Is there any technical reason why SMT is absent in Ryzen 3 cpus/apu like cpu defect or is this just product differentiation?

 

[LTC8K6]

Is there any technical reason why SMT is absent in Ryzen 3 cpus/apu like cpu defect or is this just product differentiation?

4/8 is Ryzen 5 already.

Not going to go 2/4 at this point.

Don't know about technical limits, but there doesn't seem to be a spot for a 4/8 Ryzen 3 chip.

 

[LightningZ71]

AMD uses produce segmentation for defective die recovery (though, I suspect, they are having to actually disable functional sections now to meet their product spread market volume numbers due to a maturing process tech). Given that, I suspect that AMD just isn't having that many die that have more than a couple of defective cores that are still otherwise functional to recover. Actually, it looks like R3 segmentation is likely based on failed L3 Cache cells. It looks like their 4 core parts (non-apu) all have half their L3 cache disabled. Given the reduction in L3 cache, it would likely heavily impact the ability of the processor to keep 8 threads fed enough to justify having SMT active. So, disable SMT, keep more real cores, and sell a competitive product.

 

[Insert_Nickname]

Not going to go 2/4 at this point.

The 2C/4T Athlon 200GE has been spotted in the wild. With Vega3 graphics, it would make a decent bottom-end choice. Also features a 35W TDP, so passive cooling is an option.

As to whether it will make it to retail is another matter...

 

[LTC8K6]

I would have thought AMD would not have made dual cores for the desktop these days.

 

[Topweasel]

I would have thought AMD would not have made dual cores for the desktop these days.

Seems more like a NUC like CPU and not aimed actual Desktops. But RR suffers from only having 4 cores to start with. If they didn't offer a 2c solution they wouldn't have anywhere to go with any dies with a bad core.

 

[VirtualLarry]

I could see some $300-400 laptops sporting 220GE APUs. Could be a nice budget option, should AMD pursue that avenue. Then again, they risk OEMs ONLY carrying the 2C/4T options for AMD.

 

[PeterScott]

Is there any technical reason why SMT is absent in Ryzen 3 cpus/apu like cpu defect or is this just product differentiation?

Pure product segmentation. Same reason Intel switches off HT on a lot of it's CPU's.

 

[whm1974]

I could see some $300-400 laptops sporting 220GE APUs. Could be a nice budget option, should AMD pursue that avenue. Then again, they risk OEMs ONLY carrying the 2C/4T options for AMD.

I'm thinking that for my next notebook, if I buy one, it will have at least a 4c/4t processor.

 

[SpaceBeer]

I bought laptop with 2c/4t CPU, 6GB RAM and 500GB HDD in (partially) aluminum case (HP ProBook) 6 years ago for $400. I would expect at least 4c/4t, 8GB od RAM and 256GB SSD today for the same price.

 

[VirtualLarry]

I bought laptop with 2c/4t CPU, 6GB RAM and 500GB HDD in (partially) aluminum case (HP ProBook) 6 years ago for $400. I would expect at least 4c/4t, 8GB od RAM and 256GB SSD today for the same price.

Sadly, your expectations for the laptop market are a bit too high. 8GB RAM, and 256GB SSD, NEW, starts at around $750.

 

[CatMerc]

It's product segmentation. The chances of a defect hitting a core in such a way that the structures required for SMT are non functional but keeping the core otherwise intact are basically slim to none.

 

[SpaceBeer]

There are 4c/8t, 8GB RAM, 256GB SSD laptops for €500 (inc. 19% VAT). I suppose those (or similar) could be found in US for $500.
https://geizhals.eu/acer-aspire-3-a....html?hloc=at&hloc=de&hloc=eu&hloc=pl&hloc=uk
https://geizhals.eu/hp-15-bs114ng-b....html?hloc=at&hloc=de&hloc=eu&hloc=pl&hloc=uk

The cheapest one with 4c/4t is only €50 cheaper, with HDD and uselsess dGPU (Radeon 535) I say useless, cause it's just a bit faster than IGP, but it certainly increased SUC (and price) of this laptop
https://geizhals.eu/hp-pavilion-15-....html?hloc=at&hloc=de&hloc=eu&hloc=pl&hloc=uk

Unfortunately, most of the cheaper models (around €400) come with R3-2200U, which is 2c/4t, instead od R3 2300U (4c/4t). It isalso bad decision in my opinion to use same name (R3) for these processors. Though it is still much better than 2c/4t i7 intel used up until 8th gen
https://geizhals.eu/hp-14-cm0200ng-....html?hloc=at&hloc=de&hloc=eu&hloc=pl&hloc=uk

 

[whm1974]

Sadly, your expectations for the laptop market are a bit too high. 8GB RAM, and 256GB SSD, NEW, starts at around $750.

That sounds about right. I brought a refurbished Thinkpad T430 for $170 last year and when I get around to upgrading it with another 4GB of RAM and an SSD, the total will be somewhere around ~$300.

 

[SPBHM]

It's product segmentation. The chances of a defect hitting a core in such a way that the structures required for SMT are non functional but keeping the core otherwise intact are basically slim to none.

at the end of the day yes...
but I heard that they save time by not validating HT/SMT on these CPUs, so who knows...

 

[neblogai]

Seems more like a NUC like CPU and not aimed actual Desktops. But RR suffers from only having 4 cores to start with. If they didn't offer a 2c solution they wouldn't have anywhere to go with any dies with a bad core.

Well- if there were many chips with defects in cores- they could always salvage them as 3-cores with 6 threads. Such SKU would be as capable as 4c/4t. However- they chose to release R3 2300U, which requires all cores to be healthy, and dual core 2200U. It hints at segmentation, not the need to salvage dies.

 

[Topweasel]

Not every product with reduced core count is one with salvaged dies. But you need a product that you can use salvaged dies for the ones that you need.

Not sure a 3 core CPU really has a place any more. Just not enough separation in pricing to make something that doesn't seem fit well in the product family. 2-4-6-8-12-16-24-32 cores. 3 core doesn't make sense.

 

[PeterScott]

Not every product with reduced core count is one with salvaged dies. But you need a product that you can use salvaged dies for the ones that you need.

Not sure a 3 core CPU really has a place any more. Just not enough separation in pricing to make something that doesn't seem fit well in the product family. 2-4-6-8-12-16-24-32 cores. 3 core doesn't make sense.

You only real "NEED" this if your yields are quite bad. But I don't believe yield drives core disabling to any significant extent. But instead it is just a segmentation strategy first and foremost.

For instance, Intel doesn't ever seem to use core disabled dies on mainstream sockets or laptops. It is usually only when they get to their 10+ core dies that Intel uses less than all the cores on a die.

OTOH AMD seems to almost always do this.

I don't think this indicates that AMD has bad yields, but instead, being smaller than Intel, it has always been a cost saving measure to have fewer designs taped out and in production, saving those costs. This is the driver, not bad cores.

 

[CatMerc]

at the end of the day yes...
but I heard that they save time by not validating HT/SMT on these CPUs, so who knows...

There's not much validation to do on what is basically a downcored chip that you're already using everywhere else.

You only real "NEED" this if your yields are quite bad. But I don't believe yield drives core disabling to any significant extent. But instead it is just a segmentation strategy first and foremost.

For instance, Intel doesn't ever seem to use core disabled dies on mainstream sockets or laptops. It is usually only when they get to their 10+ core dies that Intel uses less than all the cores on a die.

OTOH AMD seems to almost always do this.

I don't think this indicates that AMD has bad yields, but instead, being smaller than Intel, it has always been a cost saving measure to have fewer designs taped out and in production, saving those costs. This is the driver, not bad cores.

Intel has very high yield standards before shipping a product. I don't believe it's realistic to compare them to other fabs in that regard.

IMO downcoring does significantly help with yields. The cores are such big and dense structures that a defect is fairly likely to hit them.

 

[neblogai]

Not every product with reduced core count is one with salvaged dies. But you need a product that you can use salvaged dies for the ones that you need.

Not sure a 3 core CPU really has a place any more. Just not enough separation in pricing to make something that doesn't seem fit well in the product family. 2-4-6-8-12-16-24-32 cores. 3 core doesn't make sense.

You misunderstood. 4c/4t and 3c/6t capability is the same, but one needs fully functioning CCX, and the other- can have a defect in one of the cores. AMD chose to release 2300U as 4c/4t, not 3c/6t, that would make sense if they were having bad yields.