Which cpu for my new workstation?

Hi there.

I am building a new, affordable, workstation pc (I sold the previous one when I moved to the UK, that is why I am inactive for so long) and I am in a big dilemma regarding the cpu. This rig will be used for CAD, simulation and rendering (and casual gaming of course).
I can go for an AMD 6200 which has 6 cores at 3.8 Ghz, or for a Core i5 at the same speed.

I know that all benchmarks say Intel but is the difference so noticeable for the average user in day to day use? Most important is the price difference justified? Aren't 6 cores (AMD) better than 4 (core i5) in simulation and rendering?

Needles to say AMD is much cheaper, and mobos for AMD are also cheaper, so I can invest in more RAM and a better GPU (opinions for a GPU are also welcomed).

Note that in the office I have a HP workstation with 2 quad core Xeons, 16 GB of ram and an ATI 6670 gpu (whoever IT guy chose this GPU for a CAD workstation should be banned from working), but I don't see much difference when working in Inventor or Autocad compared with the PC I used to have (AMD Phenom IIx4 at 3.2 with 4gb ram) and a render in Showcase, or to export a drawing from autocad in pdf still takes ages.

From your experience with workstations what should I choose.

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3 Answers

I have run inventor on an HP XW6400 with a quad core Xeon 5160, a Dell T3500 with a 3GHz quad core xeon (don't know the model) and a Dell T3400 with a Core 2 Duo with between 6 - 12GB memory and Quadro 400 and Quadro 2000 graphics cards. In all cases the performance was similar for small(ish) models.

I use the IGES version of Steintrikes Mungo recumbent trike as a bit of a benchmark. This runs smoothly (zoom, pan etc) on the T3500 with a Quadro 2000 but stutters slightly on the XW6400 with a Quadro 400.

Considering the specification difference of the machines this suggests throwing masses of horsepower (certainly lots of cores) at Inventor does not necessarily achieve a great deal on the modelling side. I have only seen inventor slow down once when I had maybe 200 - 300 parts on the screen at one time.

If rendering is important, then graphics cards are very important for inventor. Switch ray tracing on in Inventor and the Quadro 400 pretty much stalls, especially with a complicated model, even when using the real time mode.

From my limited experience, multiple cores will make the system run more smoothly but don't improve Inventor much. A good spec AMD CPU is probably more than sufficient. Compare the bench marks with the Xeon 5160 3GHz and T3500 3Ghz Xeon. Any marked improvement on these will I think offer a good system.

For rendering, the best card affordable would appear to be the best solution. Any saving you can make on the CPU would be best spent on the card if rendering is important (again, not my area of expertise).

Regarding analysis, if we are talking FEA? The likes of Ansys workbench by default supports 2 CPU's / Cores. To use any more requires a more expensive licence. If cost is not a limit(?) then obviously the more cores the better. What I have learned with Ansys though is, it is better to have at least a second HDD to run the analysis files from. The analysis will hit the HDD hard, and no matter how fast the CPU, this will have a big impact on system performance... Unless you have 24GB+ ram. Most jobs will then run from memory without need of the HDD.

To summarise my ramblings...

Inventor does not need a massively powerful CPU. Oddly though, on a drawing, each view creates its own process (I read this on an Autodesk site somewhere). If you create detailed drawings with a large number of views on a regular basis then additional cpu cores could be beneficial

Rendering needs a good graphics card. But a powerful graphics card does not offer a massive performance boost to Inventor modelling.

FEA will use everything you can throw at it. Having a dedicated HDD for the analysis files is important, especially if you want to continue other tasks whilst the analysis runs. If you have only a single drive for the operating system and the analysis, the system will stutter every time the FEA hits the drive. FEA generates contiguous files, therefore a SSD will not necessarily improve performance. The only report I read suggests that SSD's only show benefit when using 4 - 8 cpu cores to run an analysis.

CAD only needs 6 - 8GB ram. FEA will eat all you can give it. I have 12GB on my machine at work and most of the small FEA models want at least 14GB. Ideally if FEA is important I recommend 24GB ram minimum.

Clear as mud...?

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It always depends on your Money....
For me as a CATIA user the "source of hardware" is the list of certificated hw at the 3ds.com site. For CAD the more important component is the GPU. (FireGL, quadro fx, ...)

Best regards

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Value for money is definitely the thing to think about. Whatever you choose, you'll no doubt want to upgrade it in a few years so there's no point spending much extra on that little bit of extra performance. For rendering and simulation, the more cores the better. An openGL graphics card is nice but not essential.

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