HP 640sfp28 aka Mellanox4 Lx MCX4121A-ACAT $29

[MountainBofh]

I've already bought so many of these its not funny. Easy to cross flash , great drivers, they just work. HPE 10/25gb Ethernet Dual Port 640sfp28 PCIe X8 Adapter - 840140-001 | eBay

 

[Escalate9725]

Are there heat concerns with putting this in something with limited airflow, like a SFF?

 

[TRACKER]

Are there heat concerns with putting this in something with limited airflow, like a SFF?

yes, there is.
I had two one to each other in desktop case with "good" airflow" and i was getting temp warnings.
These cards run pretty hot.
At 105°C you get temp warning, at 120°C you get hard shutdown.
I was finally able to stabilize my temps via adding 12cm fan located 10cm from the card and temp is now 87-89°C.
So SFF is big no no for these cards.

 

[Samir]

And here I was thinking dual 10Gb cards were the sweet spot. How well do these work with DACs?

 

[ano]

very well. we run a bunch at work.

it also uses drasticly less power than cx5/6

I need to buy some, so ehh dont buy them all before I get a chance to grab a few