Manifold no longer chases the latest processors as that just ends with storage shelves full of unused motherboards and processors that have one-of-a-kind BIOs and similarly unmaintainable prototype configurations. After a while you literally run out of storage space. For production work we have to have reliable, well-known configurations so the prototypes aren't useful there.
For tests of genuinely new hardware we rely on partners to try out builds on whatever prototypes they have. That verifies operation but it also means that usually such reports are tied up by confidentiality agreements and cannot be shared. But there are some third party observations on Ryzen.
Any useful comparisons with similarly-priced Intel CPUs (4 cores, 8 threads)?
I think the usual comparisons are against Core i7 CPUs that cost significantly more. Single-threaded the Ryzen is slower than a top end Core i7 running single-threaded. For Ryzen running parallel, AMD seem to have hit their mark. I have read reports such as:
But where the 1700 really shines is multicore productivity. We're talking about a processor that meets or exceeds the i7-6900K for literally one third of the price. I don't think there's even a question there: the 1700 is unquestionably a better value.
this is a professionals processor. Rendering, modeling, compiling code. If you do any of those, you need this for its value. It's amazing. Exactly what was advertised
The preceding generation, $99, 8 core AMD FX running multicore seemed significantly faster than 4 core CPUs that could run 8 hyperthreads which were low-end for Intel but significantly more expensive than the FX. We got a few FX units in to see just what you can get with what theory would predict to be the best performance for the lowest cost hardware configuration and everybody was totally impressed. For routine work they are great.
It is just so totally appealing to have eight real cores running 100% (the screenshots on the Radian web pages are of an 8 core FX) delivering killer performance for under $100 for the CPU that cannot be matched with a $1000+ CPU running non-parallel software. I just love that stuff. :-)
Beyond the FX there's no doubt in anybody's mind that Ryzen is a significant improvement. Initial reports of Radian on Ryzen that I have seen (all of which are from third parties) would indicate the above quotes are spot on.
better to use 8 or 16 threads
The price/performance gain of Ryzen over Core i7 at Intel's current pricing seems to be so dramatically better that I don't know anybody who has measured. I think everybody just runs 16 threads without looking any closer.
16 threads is nice just to show that Radian can do that while vendors who make misleading claims of their software being "multithreaded" cannot, but that's just a proof of principle thing. A genuine comparison, which I suppose would depend on exactly what was being done, the version of Windows in use and other factors, would be different and would require a lot of effort (as with all serious benchmarks) to set up. It doesn't seem to be worth the effort if either way you get the same or better performance at one third or one fourth the current Intel price, at least as a guide to an initial procurement decision.
Once you have the unit then yes, I suppose it would be worth setting up some benchmarks to see whether it is better or worse to have hyperthreading turned on.