The problem is that hardware configurations that work with Photoshop are not always configurations that work well for Lightroom.
To the orignal poster, who said;
That said, a B250M-BAZOOKA has been recommended as a mother board, with i7 7700K processor and 16 Mb RAM. The graphics card I have is a Radeon RX 470 4 GB discrete graphics card and my computer guy thinks that is good enough to move over to a new computer.
Usually, a "computer guy" doesn't have a good idea about what is needed for Lightroom. One of the biggest causes of slowness in Lightroom is the size of the monitor in pixels (not inches). If you go with a 1920x1080 monitor, then you don't need any specific graphics card, you can go with the cheapest one available or no graphics card if the motherboard will provide that function. If you go with a 4k monitor or larger, then you probably need a top of the line graphics card, plus, as reported here many times, brushing and spot healing causes lags in Lightroom no matter how fast your CPU and GPU are. Now the i7-7700K is a decent processor, but faster ones are available and if you can possibly afford a faster one, I would recommend that. If you are going to use a 1920x1080 monitor, go for a cheaper GPU and faster CPU. (By the way, a 1920x1080 monitor saves you money over the 4K monitor too ... ) NOTE: All of the above apply to Lightroom only, other software you have may require different/more powerful hardware.