If I may, and for future reference, if you already chose your hardware, here's my two cents.
First of all, I have plenty of PCs here. Some are older generation Intel (think circa 2017 and earlier down to 2012 with my two oldies i5-3450), but none of them are CPU folding due to how energy inefficient it is (in points per watts) in my case. On top of that, folding with a Nvidia GPU uses an entire thread of your CPU at all time, so going all in with both CPU folding and GPU folding without limiting your CPU folding cores could net in an actual loss of PPD as your CPU being at 100% would hinder your GPU efforts.
Now, from my experience with fahcore 22, GPU folding on an older generation PC in 2023 (with a CPU with a manufacture date of probably 2017 and earlier) will not be as fast as using a modern PC. As I said, I have plenty of PC with CPU manufacture date ranging from 2012 to 2017, and despite having the same GPU slotted in a full PCIe 3.0 x 16 slot (that actually runs at x16, and not one of these fake 16 slots paired to a CPU that can't even handle it), they will have an average PPD lower by anywhere between 5 and 10% compared to a modern PC. Even if I swap the GPU around, it's still the same situation, so these differences are not due to one GPU being "better" than the other by a fair margin.
Here's a few examples from my current Work units listing and these are all under Windows :
RX 6800 XT folding project 12424 :
- In a
3.0x16 slot with a i5 3450 (2012) : 4.6M PPD using 200w or so.
- In a
3.0x16 slot with a 3600x (2019) : 5.0M PPD using 170w or so (which means higher PPD with less power)
RX 6700 XT folding project 12424 :
- In a
3.0x16 slot with a i5 3450 (2012) : 2.5M PPD using 170w.
- In a
3.0x1 slot with a i3 12100F (2022) : 2.5M PPD using 120w (so yes: same PPD with less power, and in a x1 slot!)
RTX 3070 folding project 18725 :
- In a
3.0x16 slot with a Celeron G3930 (2017) : 4.2M PPD
- In a
3.0x16 slot with a i3 12100F (2022) : 4.5M PPD
- In a
3.0x16 slot with a 5600G (2021) : 4.6M PPD
In some cases, especially with AMD cards, the older CPUs really can't handle undervolting or lowering the GPU without causing a whole load of issues. On top of lower PPD, the GPU have to be kept at a higher power limit to prevent crashing. I had a lot of bad work units when I started folding again in 2022 on AMD cards due to that.
Still, as long as you choose a modern CPU with 16 PCIe lanes available to your main PCIe x16 slot and a PCIe revision of a least 3.0, you'll be fine folding with your GPU, even if you have a pretty cheap CPU and motherboard combo. For reference, most if not all CPU manufactured since 2020 are PCIe 3.0 compatible, so you shouldn't run into any issues there.
As such, the best bang or your buck build depends on your objective, but if you pay for your own power, having an efficient rig might be beneficial in the long run, which means a fairly recent Nvidia GPU (RTX 4060 Ti, for example) paired with a modern CPU and motherboard combination. If you don't pay for power for some reason, then an older GPU might be fine as you won't care too much about efficiency.