I think the summary result should be "Yes"!

Tbar's Intel-based 19 gpu slot board running 14 NVIDIA gpus with an Intel i7-6700K (discontinued) (4c/8t).
So he is basically running 0.5 cpu to 1 gpu ratios (I think I read that).

He is getting that giant RAC using 3 gtx 1070's and a lot of gtx 1060 3GB's and 1 (I think) gtx 970.

So if you already own a lga 1151 socket cpu someplace near an i7-6700K you can probably replicate Tbar's results without sinking a lot of buck's into gtx 1080's or RTX anything's. Re-use your cpu, ram, get a robust Bitcoin-based MB with a lot of gpu slots, riser card kits and.....
Move all your Nvidia gpus onto one box (actually a Mining Rack will probably make more sense). Yes you will probably need to plug a couple fairly large PSU's into the MB and different cards.

And if you already have an Amd AM4 socket cpu/ram you can hang up to 9 gpu's if you use Biostar's Am4 Mining MB (6 gpu slots plus a single 1 to 4 extender card). Still likely need a mining rack though.

Tom

I got another 1070ti and 1050ti coming in soon.

Good stuff. The power efficiency of the 750ti is impressive for such an old GPU. rated for 75W, but when I had some of them, they were only really reporting about 30-35W or so.

it's only recently with the Turing cards that they have surpassed it in the (SETI)credit/watt metric

I actually started when Seti started, 1st desktop died just after Classic, then with my laptop died July this year, now have an Acer Predator desktop only to crunch with as well as all the internet stuff, but it's fun..

your criteria listed a case with sides on it. not that they had to be plugged directly to the motherboard. Yes it was using risers. However, GPU specific server cases exist that will take 8-10 GPUs and plug directly into a daughter board with PCIe links back to the main motherboard. ASUS makes one, supermicro has one or several also. they are VERY expensive and VERY loud.

the case I used is a Rosewill L4500 that I modified by removing the HDD cages up front, and moving the center fan wall back further, and used high flow/pressure Noctua fans. this allowed me to fit the GPUs in front of the motherboard and provided enough ventilation to get the hot air out of the case so it didn't accumulate and heat up the GPUs.

if you want all the cards plugged straight into a motherboard. you will have to watercool. and you will have to use GPUs that only has 1-slot I/O, and has a full cover waterblock available. the

In this case I think the most you'd get is 7 on some high end ATX motherboards that have [7x] x16 PCIe slots. and you'd have to find one of those 7x waterblock bridges.

like this: https://www.youtube.com/watch?v=tx52HMRS5Kg

there are also some proprietary server boards with 11 PCIe slots (like my board) that you could do the same, but i imagine it would take a lot of planning and modification. no one makes an 11-GPU bridge either, so i'm not sure how to get water to them all. and as always, be mindful of power to the motherboard. USE GPUs that you KNOW use low power from the motherboard and/or use a motherboard with sufficient auxiliary power for the PCIe slots.

So far all is well running 14 GPUs, in fact, all of my machines seem to have been sedated. Even the Hackintosh isn't rebooting anymore.
Of course, there could be a thunderstorm in the next hour, resulting in a power outage, which fries everything... but for now all is well.
There are a few sales around, and one of the Mining cases has suffered a drastic price drop, with an open box being even cheaper. I ordered the open box for $60, and will give it a try,
https://www.newegg.com/black-rosewill-r2030001-0118/p/N82E16811147284 I plan on mounting 6 gpus in the box and leaving the top off.
The high-flow fans cost as much as the box, oh well, my box fan will have trouble hitting those 6 gpus mounted in the box, and at some point I may cut a hole in the side and install the top.
Seems to be a problem with exit holes on that box, including Monitor cable exit holes. I have a dremel.... and it was only $60....

After that, I may even try a 6th or even a 7th card in the Hackintosh since it's running fine with 5 cards now. The ASUS Z170-WS board has 5 pcie slots and 2 M2 slots, I have ordered another M2 converter....
Right now I'm just passing time, waiting to see if the GPU prices on eBay drop in the next week or so before buying any 'new' gpus.

What kind of results you guys getting from the 1050ti. I saw these cards on eBay for $28.99. Too good to be real?

HOLY $h!t That seems too good a price to be real. Look at Stephen's host with the dual 1050 Ti's. Not bad at all with the special app.
https://setiathome.berkeley.edu/results.php?hostid=8222433&offset=0&show_names=0&state=2&appid=

CPUs will not fry.

But they do just quit working for no apparent reason. I just have had two i7-6850K cpus go bad in the past two weeks. Temps were never higher than 60° C.