Is there a good “all-in-one” place; Or does anyone have a list of resources to workout the best cost per watt of server CPUs and hardware?
I’ve been given a task to bring rack mounted servers in house, but they have to be efficient. I’m more of a software guy and have completely lost track of what hardware is out there 
I am not aware of any single all in one information sources.
In short, here are couple things to consider
If you are going rack mounted, try not go for 1U servers unless absolutely required for density. This is due to the fact that the small 1U fans require quite bit more power per watt cooled under load. This depends on system to system case. 2U or 3U should be the better option.
Server hardware is not going to be as efficent as consumer hardware, since all the redundancies built into the enterprise models. Dual power supplies, things like that.
And I would advice to understand what kind of application you want to run, and its required computational load. You should get to understand the real power envelopes of server solutions. And understand the differences of different solutions.
Questions to be asked
How well ventilated, is the planned room for operation?
What kind of program(s) would be run, off of these server units?
What kind of hardware is necessary, for said program(s)? [minimal / idyllic alike]
How many users, would be on this server rack?
There’s a full sized rack, from floor to ceiling. Hosting mostly Python workloads, not that many users of the API as it’s not a public or sign me up SaaS. It’s systems used for specific things in insolvency.
Will also be used for development and things like that.
Do you have any idea how much compute you need and how much power and cooling you have available for your rack?
As a general recommendation I would suggest just choosing modern, current generation CPUs with a low TDP. It is almost universally the case that CPUs with a lower power ceilings and unimpressive clock speeds are way more efficient (as far as operations per watt) than those with high clocks and power requirements to match.
That said, for a project like this, I would be asking the vendor too. If you are shopping servers from Dell, HP, Lenovo, Supermicro, whatever, ask them what options they have for low power high efficiency servers.
Is this a home or work or EDU project? because IMO that really defines how we suggest things.
IMO the best w/p today but at consumer prices is in the AMD AM4 world, but getting ECC can be a challenge.
Buying used intel gear can be a great option but again finding the right combo can be a challenge. There are used Dell workstations with W chipsets that have CPU upgrade options for crazy cheap on Ebay but your stuck with their formfactors.
Talking with the big boys directly can make sense but they dont want to sell you just 1 so you may not get much of their attention.
are you o.k. with building this? or does it need to be a prebuilt device?
The compute in some services quickly gets the cpu to max when uploading large spreadsheets.
Wouldn’t mind building it myself. Although I think the boss man would prefer it done by someone else with a warranty.
The software would work fine on desktop CPU hardware. It’s Python after all and not doing any sort of GPU compute, or large request stuff.
Dell, HP, or Lenovo.
SLA’s are the difference. I might lean Lenovo since AMD has some great SKU’s for high performance low core count CPU’s that sip power when idle.
Server units for business always get pre-built by a well-rated server company. The service and support are why it costs more but you want that in business.
HP also has a fair amount of EPYC servers in their line up. i would be o.k. recommending either Lenovo or HP for this use. out of those 2 i would just check pricing with your preferred vendor and get the lower cost similar spec box.
Depending on sensitivity of data/industry you’re in, you might want to steer clear of procuring any Lenovo servers.