Hi, I was considering building a new gaming pc around march with these specs https://pcpartpicker.com/list/Q7tdXv and after some deep thought I was thinking that by the time I get all of the parts and build it Ryzen Gen 3 will be right around the corner. I don't know if I should wait to see what intel has to offer in 2020. Should I look for a Ryzen 4xxx or just pull the trigger now?
If you don't plan on building the PC until around March, I would wait until then to determine whether it's a good time to buy or not.
There will probably be some different components available by then, and prices may have changed. We will likely see new processors from both Intel and AMD next year, though I would expect for them to come later than March. And there will probably be new graphics cards from AMD, Nvidia and Intel as well, though again, most of those will probably not be coming until later in the year.
As for changes I would make to that system if you were buying now, I would probably go with a less expensive motherboard, and use that money elsewhere in the build, as it should make no difference to performance.
I would also ditch the 1TB hard drive and 250GB SSD, and go with a single 1 to 2TB SSD instead. As far as game load times (and most other real-world performance) are concerned, even an inexpensive Intel 660p NVMe drive should perform pretty close to a 970 Evo, and the 1TB 660p is only about $100. A 250GB SSD is too small to hold many games, so you would be loading them off the slow hard drive, which kind of defeats the point of having a fast SSD in a gaming system. You could of course also include a hard drive for things like backups and bulk data storage (like video), though I would look at the 2TB or larger models for that purpose, as a 2TB hard drive doesn't cost that much more than a 1TB one.
Right now the 3700X boosting to 4.4ghz will give you 110+fps in almost most of the AAA games if it's not bottlenecked by a gpu.
A 5700XT without gpu bottleneck will also give 120+fps in 1080p resolution. That might drop to ~60fps in 2k.
So 100+fps in a 144hz screen will look smooth with freesync.
Ryzen gen 3 definitely won't come by March 2020. It's more like Q4 of 2020 or starting of 2021.
What would be worth your wait is this :
Intel 10th gen on 14nm will be a slight improvement over the 9th gen regarding performance. The IPC of ryzen 3000 and Intel 8th gen are the same. But Intel takes the performance crown cuz of the higher clock speed.
Intel came out with very competitive pricing for its cascade lake aka X299 refresh cpu. So you can expect competitive pricing for the 3700X Rival. Maybe a 9900k successor at 3700X/3800X pricing?
So waiting for the cpu might be beneficial.
Almost the same goes for the gpu, Nvidia ampere is expected to launch maybe at may/June? (speculation)
So a 400 usd ampere gpu might very well give you the performance of a 2080 then. Meaning 2k 144hz gaming.
But then again, both amd and Nvidia seems to release the top tier stuff to get more sales/profit.
So if you plan on getting a ryzen 4600X and 3070, that might take it end of 2020. On a positive note, you might have stock clearance sale at second half of 2020 for the gpu.