I’d not buy a new PC with DDR4 ram.
32gb DDR4 (PC4 28800) is $84
32gb DDR5 (PC5 48000) is $155
Almost double but NOT a deal breaker for me in building/buying a PC that should last 5 years. Yes it should last way longer but I replace my work PC every 4-5 years.
@SeanB Gotcha, thanks. The 1TB I based it on has a read/write of 7300/6000 MB/s. That’s about twice the speed. I’ll look up that Samsung drive here and see what it goes for in Euro on my end!
Excellent point. Good argument as well to defend the expense to my husband 
As a soon-to-be-ex-max-user, that is not a familiar concept to me lol. I used to buy hardware that was always slightly above my requirements at that time. I usually switched anywhere between 8-10 years. I wouldnt have replaced my current mac if I hadnt started to do rendering…
I in the past did not have a good experience with MSI. Since I have had several builds with Asrock boards. All of them have been excellent with the only issue was some Bluetooth interference that was solved by moving the receiver away from the tower.
Currently, my rig is 3.5 years old and I am looking for at least 3 years before the next build.
Few things of note that caught my attention.
DDR debate
The reason this all started was to decide which is the ‘affordable’ route. I think we are bordering onto ‘preferred’ builds.
Someone here mentioned to save the money for storage and RAM. That person is right.
DDR prices will fluctuate, but longer it has been on the market the higher chance of said cost will drop, and stagnate.
The conundrum you have having with the price differences of DDR4 vs DDR5 probably due to factors outside of the data specs given. i.e. they manufacturer had a better deal, or they are using more affordable RAM modules, etc.
Personally, I would stick with DDR4 and MAX it out. As more RAM modules/sticks at some stage the super duper speeds we are all after will not work. The speeds will drop to about 3200-3600MHz when using higher amounts of RAM. So again diminishing returns.
FYI: there are motherboards that supports both DDR4 and DDR5 (not at same time) for your future upgrade options.
CPU debacle
If you’re just building this PC for SU & the occasional rendering. I would hazard to guess that the i9 would not be an optimal choice from a performance/cost angle.
The 12th Gen i7s or even i9s will be more than sufficient for SU uses, and rendering. It you are working with large rendering projects in the future you can always outsource the rendering to a render farm.
This is the general thought process that I would have gone with for building a PC.
Good/great motherboard (this will either make or break your longevity of the PC)
Power supply unit - modular (go with known brands)
RAM sticks - 3600Mhz min (go for broke motherboard limiting)
CPU i7 12th gen (you can always exchange out the CPU in the future. to 13th gen)
CPU cooler (Probably water cooled)
Storage M.2. (1 dedicated to OS, and programs. 1 dedicated as a scratch disk, 1 dedicated to Misc use) 1TB absolute minimum internal.
Nvidia RTX SKUs 3060 8GB/12GB/16GB and higher.
You’ll probably would want to swap out the provided M.2. SSD from the vendor and replace it with your own. They usually do use a slower/cheaper SSD (unless stated otherwise), also you don’t really want to rely on their sub-par SSD to install your OS.
32G seems to be the sweet spot for SketchUp
For Rendering debatable though.
I over see 2 CAD stations at work and I always budget $2,500 per station. Last station was a 4th gen i7 GTX based and current is an 8th gen i7 RTX unit. I do down cycle these PCs do other duties. My 4th gen unit is used for my CNC program and vinyl cutter as to not tie up my main pc. I might take this 8th gen i7 unit home as I do a bit at work from the house and my home PC is getting older.
I would advise against this unless budget is a concern. DDR5 has been out for some time and no sense going backwards in technology. To me this is like saying don’t use an M.2 ssd and just use an SATA SSD.
The other side of it is that it doesn’t benefit SketchUp or a renderer in a meaningful way
So you don’t think that faster ram will benefit SU? I would put $$ on faster ram and faster hard drive speeds benefiting programs that run on said computer. Just like some here will say that SU doesn’t benefit from better graphics cards BUT I tested Make 17 on my son’s PC with an RTX 3060Ti and then he upgraded to an RTX 3090 (everything else stayed the same) and his FPS in SU went from 47.24 to 61.66
I’ll stick with the hunch that newer faster ram would benefit SU
I needed a hot few minutes to wrap my head around all this
You all made very sound remarks. I prevented a panic attack by just a hair! 
I compared 12th and 13th gen CPU’s and looked them up in the table provided by @Anssi. i7 13700K and i5 13600K appear to do well.
This article (Logical Increments) suggests a setup that incorporates the i5. Given that the i5 13600K is about half the price of a 13th gen i9, I figured I would make that my swappable element in 1 or 2 years from now.
For cooling I agree that it should be a water coolant. As I want to build it in this incredibly cute chassis I should be able to fit the Gigabyte Aorus Waterforce X 280. I dont care much for the flashy lighting but it seems to come with most hardware as most is geared toward gamers.
In the article above, the RTX 3060 ti is considered an advanced solution for my needs. @JMP mentioned the same line, and given I can purchase one around € 450 (which is less than a 3rd of a 3080 ti*) I would think this makes a perfect starter GPU.
*I did see a listing of €999 for a Zotac 3080ti which is really low, but that brand seems untrustworthy and I fear it would be a bad bet.
As for what constitutes a good motherboard (I’m sorry @RLGL, the Taichi is so expensive) I am opting for the MSI MAG Z790 TOMAHAWK WIFI as it has Wi-Fi 6E 4 M.2 slots. Its price range seems middle of the road and I havent found any negative reviews. If you know of a better alternative, I would love to hear it! 
Adding to that 2x32 DDR5 Kingston Fury Beast 6000GB (not cheap ik) I am now rigged with a motherboard, fast DDR5 and a decent 13th gen CPU. Even though DDR4 seems to have little added benefit, @SeanB mentioned future proofness, and @JMP mentioned swapping out costs. Having to replace both the CPU and the RAM would be expensive (and I havent found any motherboards that support either?).
Now, storage. As is rightfully mentioned by some of you, 1TB wouldnt do. But it’s probably the easiest part to add on so I’ll start with 1TB for working storage (OS, SU and Vray), 1TB for memory swapping and misc. plus one of my older SSD’s for storage of inactive projects.
PSU is another area where I have no expertise. I think I’ll just opt of a middle of the road priced thing (Gigabyte GP-P1000GM) which is modular and has more than I will likely need with a 3060ti and affordable enough to not hurt so much in case I do need a better one.
My last purchase would then be a home license of Windows 11.
I don’t think I stayed within the $2500 budget, but its a more or less expandable setup where I am mostly planning for replacement of the CPU and the GPU, the rest of that hardware should last me a while. I think. 
I hope I haven’t offended any of you if you feel I have disrespected your advice. I have tried to understand everything you have shared with me, for which I am ever so greatful 
. I am sure I have missed out on some of the spec details, but I am hoping that this setup will still be good enough for my immediate needs and in my experience you never quite need the horsepower that you think you do (or that you want).
What do you think, am I making the right decisions?
My only comment, make sure the ram is compatible with the MB.
I just built a
ryzen 9 5900X (12 core) 3.7GHz
TEAMGROUP T-Force Dark Za (Alpha) 32GB Kit (2x16GB) DDR4 Dram 3600MHz (PC4-28800)
ASUS ROG Strix NVIDIA GeForce RTX 3060 Ti V2
ASUS ROG X570 Crosshair VIII Hero (Wi-Fi)
SAMSUNG 980 PRO SSD 1TB PCIe 4.0 NVMe Gen 4 Gaming M.2
Samsung 970 EVO Plus SSD 1TB NVMe M.2
EVGA SuperNOVA 120-GP-0850-X1, 850 G+, 80 Plus Gold 850W
Lian Li PC-O11DX 011 Dynamic
And dont forget your gonna need Fans and a good cooler for that hot Intel CPU. These are the best fans for the money and are amongst the quietest out there.
All in was around $2000, and it runs Sketchup buttery smooth.
@mrintahoe’s machine may be a DDR4 with RTX 3060 Ti. But it runs SU with no issues. As he wrote above. Ergo, it really isn’t about getting the latest and the greatest. One can’t really future proof their machines. It’s about how long you’re willing to mitigate the performance loss over time. Honestly, I would be happy with specs above.
Also, @babsgosgens. I would read up on the softwares minimum requirements for other programs that you’d use. I know that my 3D Studio Max doesn’t do well with CPU’s with low Cores & low speeds. It really needs 8C/14T minimum.
My pleasure, it also helped me keep informed of the shifts in the PC world.
I hope you get to enjoy your new PC, and best of you luck with your future endeavours.
Something to read up on for information purposes.
I am considering to change my CPU to Ryzens due to the excessive heat of the 12th gen.
Then again, it might be a great heater for the expensive gas & electricity costs. 
@JMP even with a water based cooler?
FWIW, I am using water on a Ryzen cpu.