I was hoping some one could informi f the threadripper 3970 and the 3990 are going to get new chipset motherboards- as with the introduction of the new server chipset l was hoping to buy a 3970, but with a new chipset motherboard that will support DDR5 memory whihc will make the threadripper soar.
I don't know if the upcoming Zen 3 Threadripper chips will get a new chipset or not, but DDR5 support isn't going to be part of it if they do, and the existing chipsets won't become obsolete.
If you want DDR5, you have to wait for Zen 4, which is almost certainly more than a year away for TR parts.
EPYC has twice the memory channels of broadly-available Threadripper, but only the same memory channels as OEM-only Threadripper.
Neither willl have DDR5 before Zen 4.
In general, you will get better performance with Threadripper. The GA versions have much higher clock speeds, and the ability to overclock (anything beyond PBO is not worth doing) and the OEM-only versions have slightly higher clock speeds.
The main benefit of EPYC over OEM-only Threadripper is a lot more I/O.
If your main goal is floating point, and your use-case isn't amenable to GPU acceleration, then a Threadripper 3990 is probably your best bet, provided you can live with just 256GB of memory (that's just 2GB per thread, lest you reflexively think that's plenty).
If you need more memory, then an OEM system from Lenovo with the 3995WX might be a better choice.
That's about as much as I can say at this point.