As many as you want, just use your Name, Team & passkey when you set up the client so you get Folding Credit
 
I've got three of my Folding builds in my signature

I'm running socket 1155's and folding fine. Best gpu is 1080. Concentrate on a decent gpu.

Also if you're not using linux, doing so will net you higher points. I used it back when the multi-CPU rigs [4P/BA] were tops, but I had to have a lot of help with it.  If it was me I would just try to keep adding "decent" GPU's. Glad to have you folding and or crunching with us!! 

For folding rig, I would skip the 3 Titan blacks and get a 1080Ti or 2080. Cost of electric has to be factored in the cost.
For the x99, consider an e5-1660v3 is an unlocked  8 cores 16 thread CPU. I have mine at 4.3ghz  175$ or so.
Titan 6gb, black and Z are good for BOINC milkeyway, not so great at folding this day and age with the newer GPUs.
A new GPU will do as much PPD at a fraction of the cost running it. Now sure where you live, but think of the heat the 3 will produce.
Nice in the Winter up north, but not so much in the Summer time. If you want to fold all year anyway.
 
If it is just a folding rig, find a x99 FTW or something cheaper. I have both FTW and Classy, its a great board too.
So are my Asus x99 boards, very stable and cheaper than a Classy if you can find one.
A x79 with an e5-1660v1 unlocked hexcore is an option too. Pleanty of pcie slots and pcie lanes
 

As far as Linux, it is a lot better than it used to be. I have a few boxes running Linux Ubuntu 18.4
The drivers are now in the repositories and install no problem. There are instructions all over the net "how to".
Cut and paste is your friend. Installing folding is easy now a days. There are still some PITA things happen, but lots of help out there.
I can get Linux installed, folding and crunching BOINC in a hour or so.
 
x79 and x99 xeons, the e5-16xx v1 v2 (x79) and v3 (x99) are unlocked multiplier. V4 (x99) is when they locked em up again.
If this is a folding only 24/7 box, but the $$$ in the GPU. Get the best modern GPU in your budget. 2nd hand is fine too.
I buy a lot of used hardware myself. More bang for the buck.
If say 2 1080 or 1080Ti, two 2070 or two anything, consider z370, z390 and i5-8600k or 9600k.
I like the k model for a little OC and resale value, but even a non-K can work fine for a couple GPUs
 
Good luck what ever you do. Ask questions, people here will help you out.
 
Happy holidays to you and your family.
 
 

If you are worried about temps, lower the GPU power target and set a max temp of say 75 C.
The GPU will lower clock speed obviously but the temps stay down as well.
I save one setting for folding and switch to my "max OC" setting for gaming on my main rig.
IMO the slightly lower clock speed won't hurt folding PPD much.
 
It would be interesting to compare actual numbers, but I would think you could just pause folding to game.
Even watching YouTube with hardware acceleration on my PPD goes down.
I regularly use the "Finish" option ahead of anticipated gaming sessions so I don't have a WU paused, losing bonus points while I game.
Teamviewer or Chrome Remote Desktop are good free options to control this from your cell phone when you're away.
 
I also see you are using the Pirocast folding signature, but it has not been working for a few weeks now.
You can also get a "less cool looking" free sig from EOC stats website instead (see below)