How to spec a PC

...for Engineering simulation and analysis purposes.
Computer hardware capability and prices changes daily, so how do you make informed decisions when buying a new computer?
Here follows a few principle guidelines on how to find or define the computer specification that suites your needs.
Budget
The easiest way to spec a computer is to have a maximum amount you are willing to spend, but many people don't know what a reasonable amount is.
A rule of thumb (which works well for most companies), is to spend the same amount (once off) on a computer for your engineering analyst, than you are paying him/her per month.

Just like you can't expect to spend only R50 ($3) on a sound cable for a R100 000 ($6000) sound system and expect to experience the value from the sound system, it doesn't make sense to have a highly paid employee sit around the whole day waiting for the computer to finish a task.

And if you still don't know how much is a reasonable amount to spend on a computer, leave this check box un-ticked and read on.
CPU
For CPU performance, bear in mind that the most important indicator of CPU performance per core is the Turbo clock-speed. For Nastran and Marc, a 4-core with high clock-speed will likely be faster than a 28-core with low clock speed.

The parallel licenses will also be less expensive.

Additionally, the CPU can have two (dual-channel), four (quad-channel) or six (six-channel) data-lines between the CPU and the memory. The higher the number of memory channels, the faster the data-transfer is between the memory and the CPU. Giving advice on the number of channels required is difficult because each software package has its own requirement in terms of performance requirements between CPU number-crunching ability and memory bandwidth requirements. Usually, using four cores is OK with dual-channel memory, but this is a very generic comment.
Memory
ECC (Error Checking and Correction) can only be used with Xeon CPU's while Non-ECC is for Core i3..i7. ECC is worth it as it has error checking and correction built in. It is unlikely to run into problems on non-ECC, but ECC makes it near impossible to run into any problems. If you can afford it, go for the Xeon with ECC – it is more expensive but not a lot more expensive.
Graphics
A NVidia Quadro is suggested as the first option followed by the Radeon Pro (both options are CAD-type cards instead of Game cards). The P2000 card is a good trade-off between high performance and reasonable cost. The P2200 is a slightly updated version which is faster and may cost the same. The minimum recommend card would be a P1000 if you need to save some money and is willing to settle for less performance (or the P620 if you really-really need to save money and is willing to sacrifice even more). Our experience with dual-cards are limited, but the single P2000 (or P2200) is more than good enough and will have the least amount of issues. The RTXC series is slightly newer than the P-series, but there are no options for anything less than an RTX4000 which is about R5k more than the P2200.
Hard drive (storage)

Overview of possible workstations

The preferred supplier that we use for our computers is Dell but 
Start by visiting the US Dell-site https://www.dell.com/en-us/work/shop/scc/sc/workstations?~ck=mn and running some trade-offs.

For a conservative idea of the cost of a given computer spec, look at the price before discount (The “List price” on the right) and use a R/$ conversion of about 20. This is because the local discount differs from the US and there are import duties and VAT that should be added. 

The following shows how to get to the page(s) that allow you to adjust the spec and see the price.

If you scroll down to the desktop workstations and select “5000 Series” for example: 

you’ll get to a page about the 5820 desktop workstation. Scroll down until you see “view details” (there’s a couple next to each other) and select it. 

It will bring up the Precision 5820 specs and options. There does not seem to be an updated 5-series workstation yet, although there are probably newer CPUs, Graphics and Drives. 

On this page you can change pretty much every setting available (CPU, OS, Memory, Drive(s), Graphics, KB, Mouse, Screen(s) etc.). 

A brief overview of the 3, 5 and 7 series precision is given below to help you choose.

3-Series (3630):
The “3” series is the “Baby” workstation, but don’t let that deter you. 

It can be specified with 8th and 9th gen. core i3, i5 and i7 as well as Xeon E2-series which are the Xeon equivalent of the Core i3..i7. These come with 4 up to 8 cores and all have pretty high clock speeds which are important for Nastran and Marc. Turbo speeds between 4.1 and 5.0 GHz is available. 

The 3630 can take up to the Quadro P5000 (a R26k+ card!) and has the P2200 as an option.

Memory up to 64GB with the Core i3..i7 and 128GB with the Xeon series is possible. The memory-interface is dual-channel.

It can take up to 5 SATA drives + 1x PCIe NVMe SSD drive.

5 Series compared to the 3-series:

The 5 series adds options for the even higher spec Quadro P6000 (R67k+ Card)and RTX8000 (R97k+ Card). It still has the P2000 and P2200 though.

The other difference is that it supports the Xeon W2-series. The “W” is for workstation, meaning high core-clock speeds and high core count). Examples are 4 core 3.9 GHz turbo (faster 3630 CPUs are available!) and 18 Core 4.3 GHz turbo, with options between these extremes.

It can take up to 6 SATA drives + 1x PCIe NVMe SSD drive.

Up to 256 GB RAM is possible. The memory interface is quad-channel (double the 3-series)

7 Series compared to 5 series:

Can take up to 2x Xeon Bronze, Silver, Gold or Platinum ( more names and families). The most extreme would be 2x 28-Core 4GHz turbo (at R320k+ !!)

It has mostly the same graphics cards as the 8-series with a few of the latest cards not listed: The P2000 is there but not the P2200. 

Up to 768 GB RAM is possible. Each CPU has 6 memory channels (3x the 3-series and 1.5x the 5-series).