I have done a 7900x build and have another on the way. It is an excellent processor for the right work load. What I like most about it is the flexibility it offers. Low core count tasks will get a nice clock speed boost (over 4ghz depending on how many cores as high as 4.5ghz per intel but I saw 4.7ghz stock) AND you have 10 cores for rendering or what not.

Unless you really need the 7900x core count I do not recommend x299 for any thing less (I know not everyone will agree but I have my reasons). The 8700k and even 7700k are excellent processors to fill the gaps below the 7900x.

Really comes down to how you will use it.

My sister's had her firm for many years and have used revit for a long time. There are two wait times she can get rid of: 1) wait time when working in 3d space when moving around 2) render time. She wastes so much time waiting for revit to refresh as she moves about in 3d space. Then when it comes to rendering, often it's only hours down the line when you realize there's a problem and you have to start over. Often that has a spill over effect on client meetings etc.

We want to take no prisoners when putting together a significant box. This wait time need to be become something of the past.

Would you mind elaborating on your statement I quoted?

When getting the 7900x, what other bottlenecks should we avoid (board? mem?)

for the rendering issue, I suggest the Autodesk Rendering Gallery. Buy some points to use, you can get a photo realistic image for 1 or 2 crédits and I think time saving Wise they would be Worth the "Investment" if renders are Something you produce often.
In addition you can do a quick render for 0 crédits to see what your room is going to look like and it all processes on the cloud not using your computer resource so you can keep working. So that entirely eliminates part 2 - also a render that would take 20-30 hours on your PC will be done in about 1 hour on the Autodesk gallery.

For part 1 when she is just working navigating around the model make sure shadows are off, sun path is off, and put the graphic style on uniform colors. This should reduce things enough for it to free up the model.

The way remiscs phrased it, it takes a little parsing, but I think what he was suggesting (and at least what I would also suggest) is that anything less than the 7900x on x299 (the chipset that supports Skylake-X CPU's like the i9) is a waste... e.g. you could get an i7-7820X with 8 cores, but then you'd probably be better off with the 8700K with 6 cores (z370).

As Karalon suggested, there's other ways to do rendering - the cloud is a good suggestion. GPU rendering (i.e. using CUDA on nvidia) is where most of the industry has been headed the last few years. You could consider spending less on the CPU and putting the money into a heavy-duty GPU (e.g. Titan X) and you might actually find that faster (of course you have to have something like 3DS Max software and there's a learning curve and time - Revit doesn't natively support GPU rendering)

Thanks iru69, you summed it up correctly for me (z370 is the 8700k, x399 is AMD threadripper.....and z390 will be I guess coffee lake refresh in Q1 2018?, lol marketing teams fighting over names).

@japieson

Do you have her current system specs? Rotating the models and such like you describe is I believe just single threaded CPU work so higher core clock speeds would be the remedy. Making sure hardware acceleration is on might help here but I am not sure. My clients dont have that issue with systems ranging from 5820k CPU/gtx980ti to 7700k/1080ti systems and hardware acceleration on. There was a time when drivers were not great on the 900 series and with Hardware acceleration off they still performed well.

Rendering is the real beast here. If she does not plan on moving to GPU based rendering she could go cloud based like mentioned but my clients do their renders locally so I have no feedback on that. Otherwise you are right and you have to throw cores at CPU based rendering. The 7900x would be most balanced for a revit system that needs to render. If you go above that CPU your single core speeds will start to fall off and while still an upgrade over what she is likely using; it would not be as fast as it could be when not rendering.

I mean I can keep describing possible combinations but it comes down to budget.

I'll let you know how the 7820x does...I pulled the trigger on that one for a system upgrade last week. Hope to get it all put together this weekend. I like the fact the x299 boards can support up to 128GB of Ram, 512GB if registered. Although I think with the 64GB I am getting I should be fine for quite a long time.

(Yes, this is for gaming...lol...but I still run Revit too.)

Her current spec is useless. I guess the budget is around $4k

Well some specs are important but the 7900x would be the best balanced CPU for Revit and rendering and a Revit 7900x build should come in less than $4k as well since you wont need an $800 video card (unless she wants to GPU render later).

Thank you for the help. The i9 7940X runs really well. Render in about a quarter of the time. Intel turbo max and the motherboard is cooperating. Get 4-4.4GHz on single tasks without overclocking. When rendering all cores (more that just 16 according to autodesk spec) fire up. Obviously I have cooling and it renders at about 4GHz.


Only issue I have is that Autodesk Raytracer doesn't work. It just stays at 0%. Only NVIDIA mental ray works. Still figuring out what this is all about.


UPDATE: works in 2018 trial. I guess it's a ART compatibility issue with i9 or x299 chipset


UPDATE 2:


I wanted to elaborate after further testing and for others:


The problem: Projects are mostly housing complexes / estates, convenience centers and malls. Workflow: rendering is done in Revit. A fair render takes 5 or more hours and the pc is unusable during that time. Most renders run overnight. A lot of wait time is involved. In addition the navigating in 3D with sunpath and shades etc is slow and painful.


The options: just a chip bump on i7 vs i9 vs Xeons. Custom vs off the shelf. Certainly a i7 bump assists with most tasks in revit but won’t help Revit rendering. The most wait time is around rendering. To find a Xeon alternative to an i9 with 10-18 cores on one chip is tuff. The i9 holds the top spots on the CPU benchmarks. Two Xeons on a board is at least twice the cost. Once in the i9 space one could go custom or maybe a Dell Alienware or similar, but the latter has less room for maneuver.


The rig: i9 7940X, Corsair h100i GTE cooler, 64GB 3466, MSI x299 Gaming M7 ACK, Samsung nvme 1TB ssd, Quadro p4000, 1000w power.


The result: Renders of 5 hours down to 1 hour. This was the ideal, but what we found on top was even better. We opened up 6 models. 3 are linked on 1, then two other unrelated. Two of them render, whilst we continue modeling and navigate in 3D space with shades and sunpath. These models range from 50MB to 600MB. On top we run office stuff but also a VM with autocad R14 and it remains a snap. Astounding. In single tasks with no rendering the top cores boost up to high 4-4.5GHz. When rendering runs, all the cores bump up to 3.8GHz, exceeding the 16core autodesk spec. Side note - we found that more and more tasks make use of multiple cores, like opening projects. Hovering temp is around 50 celsius, and when rendering it goes up to 70. Well within spec. No custom overclocking.


Issues: Revit 2016 autodesk raytracer does not work on x299/i9 – need to check with support but does work in 2018. Using XMP in bios shows only 6 of the 8 dimms and thus caps the 64GB to 48 GB. Apparently a known issue to be solved in future bios. For now we stick to reduced 8 dimms at 2133.