You need some serious NVidia hardware to even think about Foldingcoin and making any money.
For perspective - a NVidia GTX 1070 will fold very rough ballpark 600K PPD - this is good for somewhat less than 200 FLDC per day right now, and that has been DROPPING hard as more folks get into it.
The limited figures I've seen on the Vega FE puts it into the same ballpark as the GTX 1070 - at about double the power consumption and a TON more expen$ive.
The Vega 64 should be very close to the FE - but again, double the power consumption and quite a bit higher price.
The GTX 1080 and GTX 1080ti are faster folders, but IME not quite in line with their cost. Close though at the total system cost level.
GTX 1060 and any AMD other than the VEGA aren't worth looking at, too low of performance.
GTX 980 and 980ti were good performers as well, but again much higher power consumption. Might be worth considering if you can get one VERY cheap, and definitly worth considering if you already have one.
Don't try using a "mining" type rig with a low end CPU on folding.
I had a rig with 2 x 1080ti and a Pentium G4600 dual core - and the CPU was LIMITING the peformance of the pair of GPUs badly.
I verified that when I moved one of the 1080ti cards to a 3-card machine with a FX 8320E OCTOcore CPU and watched the PPD go up almost 50% on some projects (and about 20% overall).
Don't even think about using 1-lane risers (like the VERY COMMON USB-type ones most mining riser rigs use) - it's been tested that PCI-E 2.0 on an 8-lane connection measurably impacts PPD (almost 10% as I recall) vs a 16-lane PCI-E 2.0 connection, and a 4-lane connection impacted by somewhat OVER another 10%.
PCI-E 3.0 8-lane seems to be enough for most GPUs to achieve full PPD - for now....
Figure AT LEAST one fairly high end CPU core per GPU even for the 1070 and 1080, and more like 1.5 per 1080ti (and DO NOT COUNT Hyperthreaded Cores, they don't help worth SQUAT).
It's entirely possible to be profitable working Foldingcoin, but if you're "all about the profits" there is usually other stuff you can mine that will make you more on a given card.
Final point - FoldingCoin only pays out once per month, USUALLY during the first week of the month.
Yes, I agreed as I have been tested with pic-e 1x riser and the performance dropped for my 1070. So, it is better to plug 1070 directly to x16 pci-e on motherboard. And 1 cpu thread will be used while mining.