For VR 7800X3D vs 7950X3D(more cores)?

[-Relax-]

So whats better??
 know new gen is comming but i just wonder if VR will profit from more cores here??
 

here it looks like more cores helps with the multithreading!? (even its SP test with not lots units and so on)

[Mr_sukebe]

My understanding is that no, more cores don't help.

From what I've read:

• AM4 and AM5 chips are manufactured such that each chip has two CCDs.  Each of those CCDs has 8 cores
• In the 7800 and 9800 versions, one of the CCDs is disabled, hence why it has just 8 cores available
• The x3d versions has it's special v-cache, but that's only provided for the primary CCD,, the other CCD doesn't have it.  This results in a performance variation between each of the CCDs.  In addition to that, if both CCDs are in use, then need to coordinate with each other, which can induce latency
• Not having the 2nd CCD in the x800 version means that the non-used CCD doesn't need to be powered, which saves power and reduces heat dissipation requirements for that CCD

In short, the benchmarks I've seen show that the x950 variants are actually slower than the 8 core versions for gaming.

So save your cash, buy the x800 version.  Hopefully AMD will at some point start offering 16 and 32 versions where all cores have access to the V-cache.  Unfortunately, we're not there yet.

 

[Aapje]

No, 7800X3D's come in two variants, with 1 CCD and those with 2.

Basically, they create a bunch of CPUs with two CCDs and 3D V-Cache. The ones that are fully functional get sold as 7950X3D. Those that are a little bit broken get sold as 7900X3D, where 2 cores are disabled on each CCD. Then other chips have a completely broken CCD or connection between the CCDs and they get sold as 7800X3D. But demand is greater than what can be supplied with these partially broken chips, so they also create CPUs with 1 CCD and 3D V-Cache. These get sold as the 7800X3D if they are fully functional and if 1 or 2 cores are broken, they get sold as a 7600X3D with two cores disabled.

In general, a crucial aspect of manufacturing CPU and GPU chips is to make sure that those with defects can still be sold, for a lower price. It is much more expensive to have to toss a CPU/GPU chip in the trash, rather than sell them for a lower price.