Which processor, memory, and GPU will support your CAD software — and your users — most effectively? Learn how to make smart choices when specifying your next purchase.
The CAD Manager’s Newsletter explains the technical basics of workstation components and the financial advantages of buying the right hardware — not the cheapest.
The Processor — Feeding the Need for Speed
Most commercial CAD software programs today still process the bulk of their task load on a single core. This means that it isn’t the number of cores on the processor that determines how well your software will run, but the maximum speed of the processor that matters. Even software applications that handle large data sets, such as Revit, Inventor, SOLIDWORKS, and MicroStation, fit into this single-core operation paradigm.
So, unless you’re running massive parallel analysis processes or rendering motion picture–level videos, the processor best suited to your purposes will almost always be the processor with the highest frequency, known as the clock rate. For typical CAD tools and workloads, it is better to have a 4-core processor running at 4 GHz than an 8-core processor topping out at 3 GHz, for example.
Purchasing recommendation: Workstations with the fastest processors only cost a little more than their slower counterparts, yet deliver substantially better CAD performance — so max out the clock rate.
Senior management note: Buying anything less than the fastest 4-core processors we can afford is a false economy. If we can invest an extra $200 in a workstation that will save countless processing hours during its three-year lifespan, we’re getting a great return on our investment.
RAM and Disk Subsystems — Maximizing the Essential Support Staff
But having a fast processor is only part of the answer, because all the other systems in the workstation have a role to play in making sure the processor can operate at its maximum speed. Just as you wouldn’t buy a race car with a go-cart engine in it, you shouldn’t buy a fast processor without putting the appropriate supporting components into your workstation as well. Consider the following:
Memory. If the processor doesn’t have adequate random-access memory (RAM), then it must go back and forth to the system disk to work with data. The data channel speed from the processor to the RAM is optimized to feed the processor at maximum speed; the disk speed may be way, way slower in comparison.
Some rules of thumb for getting the right RAM in your machine:
- Purchase the fastest DDR4 RAM that your processor supports. Newer machines typically use DDR4 2133 MT/s modules, but the processor specifications will tell you the exact values.
- Put the same size of RAM module in all memory slots. For example, if your machine has two memory slots it is better to install two 8-GB modules than a single 16-GB module so that both memory channels can be used. And be sure to get the same speed in both modules.
- Consider 16 GB the minimum for CAD workstations; 32 GB is better, because software will get more complex and models will grow larger over the lifespan of the workstation, thus making more RAM desirable.
Disk speed. Of course, the processor and RAM must load the operating system, CAD software, and CAD data from somewhere, and that somewhere is the hard drive. The fastest available technologies now are NVMe-based solid-state drives (SSDs) that can read/write data at roughly 2,500/1,500 MB/sec, while older SSDs can only provide read/write speeds of 550/500 MB/sec throughput. Mechanical hard drives — an older technology that uses spinning disks — only provide about 100 MB/sec read/write performance. With this comparison, the writing on the wall becomes clear: the difference between a hard disk and a new-generation SSD is about a 20X improvement in speed, for only a $300–400 increase in cost!
Ultimately, the processor can’t do its job properly unless your disk and RAM subsystems can move the data quickly. And the cheapest single thing you can do to make those systems fast is to purchase the best SSD you can afford.
Purchasing recommendation: Buy 32 GB of the fastest RAM your workstation will support, along with a 500-GB NVMe-based SSD. Instead of creating a bottleneck, these components will allow you to squeeze every bit of power out of your processor for the life of the workstation.
Senior management note: Optimizing these components will give us the fastest CAD workstations to power through CAD-intensive tasks such as building information modeling (BIM) and mechanical modeling. When you consider the number of hours these upgrades will save our high-cost engineers and designers, you’ll see it’s the smart financial decision to purchase these low-cost components now.
Getting Just Enough Graphics Capability
Which GPU (often referred to as a graphics card) to purchase is always a subject of much debate (and vendor hyperbole), but the good news is it doesn’t have to be a complicated decision. Here are some general guidelines to consider as you decide on which GPU to specify:
What will your monitor resolution be? Be certain that the GPU can handle commonly used monitors (which would now be full HD [1920×1080] or 4K [3840 x 2160]).
How many monitors will you use? Be sure the GPU can support typical requirements — which is often two or more monitors, for CAD purposes. Be sure the connectors on the GPU (HDMI or DisplayPort) are compliant with your needs and/or legacy monitors.
Which software applications will you use? Purchasing a GPU that is certified for your software will radically reduce configuration glitches and problems.
Will you be doing primarily 2D work, 3D work, 3D work with animations, or something else? As tasks move from 2D up to 3D with animations, the amount of GPU memory required will go up as well. While a 2-GB GPU would be fine for most Revit or SOLIDWORKS workflows, more could be required if real-time animation and visualizations are required.
Purchasing recommendation: Buy the GPU that meets — but doesn’t exceed — your current needs. Should your software needs change in the future, you can upgrade GPUs (unlike processors).
Senior management note: If we need to cut costs on our new workstations, the GPU is one place we can do it. But in the case of an expensive GPU, be sure to also get the 500-GB SSD recommended above so the investment isn’t wasted!
Mobile Workstations — Different Format, Same Goals
When purchasing laptop computers or mobile workstations, remember that in general, a laptop for CAD should be configured just like a desktop workstation for CAD. All the same recommendations apply.
In a world of confusing CAD software claims and changing operating environments, two universal truths still exist: Fast is better than slow, and hardware is cheap compared to expensive engineering and design labor. Over the years, I’ve found this rhetorical question very useful when speaking to senior management: “Why is it acceptable for an engineer who makes $80,000 a year to waste valuable time crashing an old workstation several times a week, but a $2,500 new workstation is ‘too expensive’ to fit into the budget?”
>> By Robert Green, Cadalyst, February 22, 2017