Engineering PC DDR4 RAM CAS latency vs speed

[paulsch]

I am building a performance computer mainly for CAD and CFD/FEA simulation software. I will mostly be using Autodesk products but i may run Siemens NX as well.

Which RAM is better for my application? I am running 4x8GB for 32GB total.
DDR4 2133, CAS latency 12, timing 12-12-12-35
or
DDR4 2400, CAS latency 15, timing 15-15-15-35
or
something else

Does it even matter?

Please explain, this is my first serious performance build and I've seen so many conflicting arguments on this topic.

The build (these parts aren't final but similar in spec to what I'll use):
-Intel Core i7-5960X Haswell-E 8-Core 3.0GHz Processor
-ASUS X99-Deluxe SATA 6Gb/s ATX Intel Motherboard
-Will use a SSD and a high performance graphics card
-Windows 8.1 and beyond

 

[Pinhedd]

I am building a performance computer mainly for CAD and CFD/FEA simulation software. I will mostly be using Autodesk products but i may run Siemens NX as well.

Which RAM is better for my application? I am running 4x8GB for 32GB total.
DDR4 2133, CAS latency 12, timing 12-12-12-35
or
DDR4 2400, CAS latency 15, timing 15-15-15-35
or
something else

Does it even matter?

Please explain, this is my first serious performance build and I've seen so many conflicting arguments on this topic.

The build (these parts aren't final but similar in spec to what I'll use):
-Intel Core i7-5960X Haswell-E 8-Core 3.0GHz Processor
-ASUS X99-Deluxe SATA 6Gb/s ATX Intel Motherboard
-Will use a SSD and a high performance graphics card
-Windows 8.1 and beyond

If you're building a computer for CAD work you should build (or buy) a workstation rather than a personal computer.

First, I highly recommend looking at OEM products from the likes of Dell and HP. Their business support is excellent, if something goes wrong they'll usually have a replacement at your doorstep within 48 hours so that you can get back to work ASAP. A similar failure using commercial off the shelf components would require a 4-6 week RMA and depending on the failed component that may mean 4-6 weeks of downtime. If this is a mission critical workstation, and it sounds to me like it is, pay the little bit extra that it takes to make sure that someone else is standing by should something go wrong.

Second, if for some reason you feel comfortable building it on your own and are willing to accept the risk of prolonged downtime, don't use consumer grade components.

Purchase a Xeon E5-1650 v3 or a Xeon E5-1660 v3 and throw it in an Asus X99-E WS. If money is not an obstacle and you wish to use a dual-socket platform, that can be done as well but it will require a bit more thought.

Get 32GiB of DDR4-2133 at JEDEC standard configuration. Don't overclock workstations. EDIT: make sure to get DDR4 ECC RDIMMs.

Same principle goes for your SSD, either get an enterprise one (Intel 710 series for example) or get a redundant pair in RAID-1. That way, if one fails (and SSDs do fail, often), you'll still be able to work and your data will be intact.

As for the GPU, use a professional GPU, not necessarily a high performance one. AutoDesk pays AMD and NVidia a truckload of money to work specific tweaks and assurances into their FirePro and Quadro drivers that aren't present in their consumer equivalents. Some CAD software products will not work on Radeon or GeForce branded GPUs.