The Truth About Chips

Last month, AUGI magazine ran an article titled What is The Best Computer for Revit, although the article goes into what management, the ‘superstar’ and the user requires, to be frank some of the advice within was absolutely terrible. The final paragraph states:

openquote..whatever level of workstation The User and The Superstar gets, ensure the best Xeon with the most multicore processors..  

..and get the most RAM above 64GB you canclosequote

If you haven’t noticed yet, I’m a bit of a nerd. I don’t just work in BIM every day with a background in hydraulics design, I also have a background in IT. I used to work as an IT Manager in an engineering firm and I have studied a Cisco Certified Network Associate (CCNA) course. Even though I’m no longer working in an IT role, as BIM Manager part of my job is assisting the IT team testing and recommending hardware for various roles within the company. Understanding engineering hardware requirements and purchasing hardware that not only fits those requirements but also fits a reasonable budget has been part of my job for years.

The statement from the article that your company is “absolutely broke and doesn’t really care as much about lost $$$ and productivity” if they’re only giving your machine 32gb of RAM is laughable, but my biggest gripe with the article is the recommendation on the processor.

For the non-techies out there the processor, or the CPU, is the chip that is the beating heart of your computer. Unfortunately a lot of people (maybe your Mum) thinks that the CPU is “the box”. It’s not the box, it’s inside the box! There are two players in the consumer market for desktop and laptop CPU manufacture, Intel and AMD. Intel has been king of the hill for a number of years now in both the corporate and enthusiast markets, however AMD is working on a big comeback with the release of their new chips in the next 6 months.

Let’s see what was recommended for the processor from the AUGI article

cpu

openquoteProcessor
Xeon multicore processors. Get as many and as robust cores as your $ allows. Did someone say 44 cores and 512GB RAM? Yes, I just did. You can and someone should check processor ratings and speeds at CPUbenchmarkclosequote.net

Ignoring that no one seems to have proofread the article, lets have a look at this pie in the sky suggestion. At 44 cores we would be looking at the recently released Intel Xeon E5 2699v4.

For the tech guys that’s a 22 core, 44 thread Broadwell based CPU that runs a base frequency of 2.2ghz and a turbo frequency of 3.0ghz.

For the non-tech guys out there, it’s some of Intel’s latest technology released in the first quarter of 2016. It’s also a CPU that retails for AU$7526.74. That’s just the CPU. No RAM. No hard drive. No case. That price is actually the cheapest I can find the chip for in Australia. Admittedly there is a little bit of Australia tax included as prices in the USA start at around US$4644(AUD$6169) but that’s still the kind of budget you’d normally have for an entire high end Revit machine.

So with 22 cores/44 threads and AU$7500 less in your pocket, what exactly can Revit do? Let’s take it from Autodesk themselves, their knowledge network has a handy article titled Which function in Revit will take use of multiple processors. When they’re referring to “multiple processors” they’re talking about multiple cores or threads. A core is a physical CPU core on the chip where as the number of threads is how many simultaneous actions the CPU, these show up as another core on the CPU if the CPU supports technology called Simultaneous Multi Threading (SMT). People incorretly say that a CPU has 44 cores, when in fact it has 22 cores but it’s able to simultaneously process 44 threads. Intel calls their version of SMT Hyperthreading, where as currently AMD do not support SMT on their CPUs. AMD however will be introducing SMT on their soon to be released Zen chips.

From Autodesk:

Multi-threaded processes in Revit 2017:

  • Vector printing
  • Vector Export such as DWG and DWF
  • Autodesk Raytracer
  • Wall Join representation in plan and section views
  • Loading elements into memory. Reduces view open times.
  • Parallel computation of silhouette edges
  • Translation of high-level graphical representation of model elements
  • File Open and Save
  • Point cloud data display
  • DWF Export as individual sheets utilizes multiple processes.
  • Color fill calculations are processed in the background on another process.
  • Calculation of structural connection geometry in the background

If you’re rendering all day every day and that’s all that you’re doing, then the E5 2699v4 would serve you well. If you’re not rendering all day every day, you’d want to hope that you’re connecting a hell of a lot of walls, bucket loads of vector prints and not much else. Sure that’s an oversimplification, however when you sit down and think about what you really do every day in Revit, you can see that for the most part a single core is all that is needed. You could argue that Revit also uses multiple cores for opening and saving files so that’s something! You save to central every 15mins as you should! The reality of it is that when you’re opening and saving files you’re not limited by the CPU, you’re limited by the speed of your hard drive and more so, your network.

A great source of information for CPU performance is the Passmark CPU Benchmark site. Passmark gathers their information from benchmark tests run on hundreds of thousands of computers with many different configurations, this allows Passmark to be able to provide rather accurate results of how one system performs relative to another. It’s as simple as checking out the tables – the higher the number, the higher the relative performance of that CPU. A CPU with a score of 4000 will process roughly twice as much data as a CPU with a score of 2000. When comparing the best CPUs for Revit, the two that you want to look at are the Single Thread Performance charts for your day to day workload and the High End CPU charts for multi threaded work such as rendering.

Looking at single threaded performance for day to day work, that $7500+ CPU is going to perform about as good in Revit as a $76 Haswell based Pentium, the $76 chip runs single threaded applications at 98.6% of what the $7500 Xeon E5 2699v4 is capable of.

2016-09-12_14-16-48

It’s an extreme example and I’d never ever suggest buying the G3250T for a Revit machine, but it shows just how silly the suggestion of “the best Xeon with the most multicore processors” really is. In fact it’s a fairly poor recommendation for rendering as well as the CPU that is king of multi-thread performance, outperforming our 44 thread xeon by 20% only has a lowly 20 cores/40 threads!

2016-09-12_15-11-48

But being outpaced by a CPU with 2 less cores isn’t the only reason why it’s a bit of a silly chip for Revit..

So what actually is the best processor you can get for Revit?

As you’ve probably figured out by now, that actually depends on what your daily tasks consist of. Autodesk actually tell you what you should consider in their system requirements page on the knowledge base. When reading through the system requirements, you need to understand that the minimum requirements are just that. The minimum requirements to run Revit and not much else. If you’re modelling an average size house or a kitchen remodel, the minimum is probably fine. Anything beyond that, you need more power!

Jumping straight on up to Autodesk’s performance specification, they recommend

openquoteMulti-Core Intel® Xeon®, or i-Series processor or AMD® equivalent with SSE2 technology. Highest affordable CPU speed rating recommended.closequote

The next sentence states

openquoteAutodesk® Revit® software products will use multiple cores for many tasks, using up to 16 cores for near-photorealistic rendering operations.closequote

The emphasis on both those sentences are mine, but it’s quite important. The highest affordable CPU speed rating is really geared toward your everyday workload, this is the single thread performance. We already know from Autodesk’s multi-threading article that there is a small list of things that actually use multiple cores, but then the core count quite clearly highlights if you go out and buy a 44 core CPU for Revit, you’re going to be wasting 28 of those cores/threads. Anything over 8 cores/16 threads is simply wasted.

If it’s for your daily grind in Revit and your daily grind is like everyone else’s; churning out models, then you want the fastest single threaded processor you can get your hands on. At the moment, this is still the Haswell based Devil’s Canyon, otherwise known as the i7 4790K. It’s an AU$489 4 core/8 thread CPU which comes in at 150% the performance of the 44 core chip. If you want to stick to the Xeon brand, and there are good reasons to, the chips of choice are the Xeon E3 processors which are targeted toward single threaded applications. The fastest E3 currently on the market is the E3 1281v3 which retails for around AU$500 and has almost identical performance to the i7 4790k.

Multi-threaded tasks which let’s face it, the only one worth worrying about is rendering, it’s a different story. If rendering is your day to day job you need to look at a Xeon E5 chip. They’re targeted to multi-threaded workloads. Currently the E5 chips available are based on the Broadwell variant of the i7 lineup, at 8 cores/16 threads the pick of the bunch would be the E5 1680v4 and the E5 2667v4 but these still retail at AU$3018 and AU$3478 respectively for the CPU alone. You’re in luck though if you want the performance and aren’t tied into the big corporate PC companies, an ‘E’ series i7 chip might be just what you’re after. The 8 core / 16 thread i7 6900K CPU comes in at AU$1534 and matches the E5 1680 in performance in both single and mutli-thread applications.

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