There are various threads on PC specs here at the forum - one especially that compares system performance with a standardized “benchmark setup” in Cantabile:
Key points to watch from my side:
- “full” PC setups tend to be less problematic with live audio than laptops or NUCs (built on laptop chipsets) - the power management features of laptop chipsets get in the way of smooth audio performance and are really tricky to tame
- No need to go completely crazy on CPU - a last-generation middle-of-the-road Core i5 does the job nicely without breaking the bank
- RAM (>=32 GB) helps with large sample-based instruments, SSD with loading times
- audio interface is crucial for smooth live audio performance at low latency. There are some with very efficient drivers that have proven themselves for live use - the RME Babyface / Fireface range is still at the top of the list (both performance and cost, unfortunately). Zoom builds nice and efficient interfaces; also the Behringer U-Phoria range seems to perform surprisingly well for its low price.
- investing in expensive graphics cards isn’t necessary for a live PC - on-board graphics integrated with the CPU are perfectly fine for audio applications.
There’s really no need to invest massively to get reasonable audio performance - my “Live Cube” built on an ASRock DeskMini platform (small two-liter mini-PC box) with an i5-9600K CPU (on-chip graphics) and 32 GB of RAM works perfectly well for my live requirements, which are quite complex.
My current live set contains 170 plugins pre-loaded, with a working set memory of rougly 9 GB. My system runs all of my songs (some of them very complex setups of up to 50 loaded racks) without breaking much of a sweat at 128 samples / 44.1 kHz, single-buffered, using an RME Babyface classic audio interface.
This “Live Cube” cost me around 800 EUR to source the components (excluding audio interface cost) and 2 hours to assemble; you can also find people who sell them built-to-order.
Of course, I have optimized my live setup quite a bit over the years, throwing out the CPU- and memory-hogs in favor of leaner plugins - “good enough is good enough” for live use…