E7 8891 v4 10C - $69 OBO

[vintagehardware]

This is the frequency optimized version of E7 v4: 2.8GHz base and 3.5G max turbo 60M L3 cache. It's a decent price if you have a E7 barebone lying around.
Here is the link: E7 8891 V4
Seller accepted $50 for 4. Not too bad for $200 you get 40 broadwell HF cores.
I know E7 systems are very rare now on ebay. Not like last year this time when you could get SM or other E7 barebones relatively cheaply.

 

[EasyRhino]

this is super not going to fit in my 2011-3 E5 motherboard, is it?

 

[NablaSquaredG]

this is super not going to fit in my 2011-3 E5 motherboard, is it?

Nope, no way.
Xeon E7s use Intel SMI(2) (Intel Scalable Memory Interconnect) which requires a special memory buffer (e.g. Jordan Creek), opposed to E5s where the memory is directly attached to the CPU.

 

[vintagehardware]

Another warning: 4 of these in a loaded system may cost you about 1kw when running at 100%.

 

[NablaSquaredG]

It's not that bad.

My Quad Sockets (Cisco C460 M4, Supermicro 8048B-TRFT / X10QBi), 1TB RAM each, need about 800W with PSUs in Grid Config (all active)
2TB RAM should be just below 1kW

 

[mimino]

Darn you people are throwing some crazy numbers around here