Depends on the app really. Some BOINC projects only need 10s of mb per task. Any EPYC board will have plenty of RAM slots though. It does seem like the CPU core count has been increasing faster than RAM density lately.

How much did that cost you?

They are definitely not cheap. List price for the one I had configured runs close to $14,000USD. My Dell rep was able to get me about $5,000USD in discounts so it came in under $10,000. The reseller wanted $12,000 to $15,000 depending on how options were configured. Didn't make sense to me as that is the list price of a brand new machine with a 3 year warranty.

Those machines START at about $2,000. That's a single low end EPYC processor with a minimal amount of memory, perhaps one cheap HD etc. The R7425 can be configured all the way up to a 2 processor 64 core machine with SSDs, TBs of memory etc. A top of the line R7425 will probably cost between $30,000USD and $40,000USD. Top of the line EPYC processors run about $3,000 each so if you get 2 in the box, you've spent $6,000 just on processors, add another $6,000 for a reasonable amount of memory(registered, ECC) to justify your processor expenditure, throw in a couple of enterprise class SSDs in a RAID configuration at over $1,000 a piece, plus the RAID controller and it it adds up fast.

Here's a sample configuration from a reseller that only has the 24 core processor:

DELL EMC R7425 24 X 2.5 INCH SERVER 2 X EPYC 24C 7451 768GB 24 X 3.84TB SAS SSD
$38,729.00 - Conf # P706649

I'm relatively new here, but I'm curious to if you are using your R7425 for anything else besides World Community Grid? What are the reasons that you chose to purchase the R7425 at a relatively high cost, compared to say building multiple Threadripper computer builds for roughly the same money?