Building a 128-thread cruncher?

[Dirk Broer]

Now EPYC has arrived in the shops, as well as the EPYC boards, let's take a look at the offerings.

Cheapest board (here at least) is the Supermicro H11DSi at 560 Euro, which is a dual Socket SP3 board.
As all SP3 boards offered here have 16 RAM slots, and the EPYC boards do not have a chipset because EPYC is a SOC, we go for the Supermicro
The five you can get here (Gigabyte, Tyan and three Supermicro) are all form factor EATX, so when you have a EATX case: you're in! Otherwise you need an EATX case.

You might need a new PSU too, and when you're into servers and have a decent casing you might consider an extra redundant power supply, which takes over in case the first fails.
The boards support up to 2TB of RAM, and for dual CPUs it is recommended that memory be populated equally in adjacent memory banks.
You might consider buying smaller ECC Registered modules at first than the 256GB modules that are maximally supported, as you need [TTBOMK] eight modules per CPU, EPYC having octo-channel RAM.

EPYC 7501 is the least power-hungry of the 32-core EPYCs at 155-170 Watt and they cost 3899 Euro each....ouch! Still much cheaper than the equivalent Intel offering though...

When you are into single socket EPYC the 32-core EPYC 7551P can be bought for 2399 Euros

You can also decide to wait for Starship and crunch on less cores until that launch. 16-core EPYC 7301 only costs 887 Euro, which is slightly cheaper than the -significantly faster- Threadripper 1950X.

CPU/SOC	Cores	Socket	Mobo format	TDP	Speed	TDP/Thread
Threadripper 1900X	8	TR4 single	ATX-EATX	180 Watt	3800-4000 MHz	11.25 Watt
EPYC 7251	8	SP3 single-SP3 dual	EATX-EBB-Proprietary	120 Watt	2100-2900 MHz	7.50 Watt
Threadripper 1920X	12	TR4 single	ATX-EATX	180 Watt	3500-4000 MHz	7.50 Watt
Threadripper 1950X	16	TR4 single	ATX-EATX	180 Watt	3400-4000 MHz	5.63 Watt
EPYC 7351P	16	SP3 single	EATX-EBB-Proprietary	155/170 Watt	2400-2900 MHz	4.84-5.31 Watt
EPYC 7281	16	SP3 single-SP3 dual	EATX-EBB-Proprietary	155/170 Watt	2100-2700 MHz	4.84-5.31 Watt
EPYC 7301	16	SP3 single-SP3 dual	EATX-EBB-Proprietary	155/170 Watt	2200-2700 MHz	4.84-5.31 Watt
EPYC 7351	16	SP3 single-SP3 dual	EATX-EBB-Proprietary	155/170 Watt	2400-2900 MHz	4.84-5.31 Watt
EPYC 7401P	24	SP3 single	EATX-EBB-Proprietary	155/170 Watt	2000-2800 MHz	3.23-3.54 Watt
EPYC 7401	24	SP3 single-SP3 dual	EATX-EBB-Proprietary	155/170 Watt	2000-2800 MHz	3.23-3.54 Watt
EPYC 7451	24	SP3 single-SP3 dual	EATX-EBB-Proprietary	180 Watt	2300-2900 MHz	3.75 Watt
EPYC 7551P	32	SP3 single	EATX-EBB-Proprietary	180 Watt	2000-2550 MHz	2.81 Watt
EPYC 7501	32	SP3 single-SP3 dual	EATX-EBB-Proprietary	155/170 Watt	2000-2600 MHz	2.42-2.66 Watt
EPYC 7551	32	SP3 single-SP3 dual	EATX-EBB-Proprietary	180 Watt	2000-2550 MHz	2.81 Watt
EPYC 7601	32	SP3 single-SP3 dual	EATX-EBB-Proprietary	180 Watt	2200-2700 MHz	2.81 Watt