Question Is Infinity Fabric used on all Ryzen processors especially the 5700x

[r_scooter]

I have a 3700x right now and am upgrading to a 5700x. My question is about Infinity Fabric. I know the 3700x uses the infinity fabric to put together 2 4x4 core processors to make an 8 core processor. I am choosing to upgrade to a 5700x and wondering thoughts about the upgrade, not just is it worth the upgrade but mostly performance. For example, with my 3700x in some games like Dues Ex Mankind Divided I had to set the CPU affinity to only use 8 threads instead of all 16. I believe this is because of the Infinity Fabric. I have found plenty of articles supporting that the 5800x doesn't use Infinity Fabric and is physically 8 cores instead of 4x4. But is the 5700x I am upgrading to also 8 physical cores or is it also 4x4.

 

[Ajay]

The problems with the number of cores/threads with some games is the game code itself, not the CPU. Depending on the GFX card you have, the 5700x would make a nice upgrade for game. Not stupendous, but nice - without having to buy a new motherboard/RAM, etc.

 

[maddie]

I have a 3700x right now and am upgrading to a 5700x. My question is about Infinity Fabric. I know the 3700x uses the infinity fabric to put together 2 4x4 core processors to make an 8 core processor. I am choosing to upgrade to a 5700x and wondering thoughts about the upgrade, not just is it worth the upgrade but mostly performance. For example, with my 3700x in some games like Dues Ex Mankind Divided I had to set the CPU affinity to only use 8 threads instead of all 16. I believe this is because of the Infinity Fabric. I have found plenty of articles supporting that the 5800x doesn't use Infinity Fabric and is physically 8 cores instead of 4x4. But is the 5700x I am upgrading to also 8 physical cores or is it also 4x4.

Infinity Fabric exists in all modern AMD products. I don't know if you can shut off 4 cores on Zen3 products, but why not just turn off SMT and run the cores in single thread mode. 8C - SMT should be much faster than 4C + SMT.

 

[Hail The Brain Slug]

I think the issue OP is referring to is with the old 4+4 layout of chiplets in Zen 2, where games with threads spread across both CCXs would pay a sizeable performance penalty due to the latency for a thread on one CCX needing to access data in the L3 of the other CCX.

Zen 3/5700X still uses infinity fabric to connect the chiplet to the IOD. However, you are correct the Zen 3 chiplet design is 8 cores all in one CCD/CCX, so there is no latency penalty for all 8 cores to be utilized by a game.

The dual CCD SKU's like 5900X and 5950X still can see this issue if games have threads scheduled across both CCDs.

Windows makes an effort to group threads from the same process on one CCX/CCD, but games may spawn dozens of threads or more, and windows doesn't really know how to handle that besides placing them on idle cores on the next CCX/CCD. This is why locking affinity of a game to one CCX/CCD helps, since then windows has no choice but to just spam all the threads onto your selected CCX/CCD.

 

[A///]

Windows makes an effort to group threads from the same process on one CCX/CCD, but games may spawn dozens of threads or more, and windows doesn't really know how to handle that besides placing them on idle cores on the next CCX/CCD. This is why locking affinity of a game to one CCX/CCD helps, since then windows has no choice but to just spam all the threads onto your selected CCX/CCD.

I saw through an mlid video yesterday while nursing a large bottled of iced in a bucket white wine where he had some game developer with him and the guy was discussing how threading becomes a complicated manner on intel and amd systems, and how if intel drops smt/ht it'll become an interesting engineering feat especially as intel plans to move to compute tiles too. then went on to talk about how ue5 is difficult to work with as a developer indie or at a big studio. there isn't sadly enough pressure on microcrap to design a better thrad handling system.