The Logitech K840 had testers happy with its exceptionally low latency and relatively quiet typing noise. Expert testers from Rtings did not notice or complain about any lagging during their tests, and they were also pleased with typing quality. They credited their good typing experience to the keyboard’s Romer-G Tactile key switches, which they also credited as the main reason why its typing noise was very low. As a result, they deemed it fit for office use, Reviewers from 9to5 Toys were also impressed with the K840’s build quality, as they found it quite sturdy.
However, product reviewers were not very happy with its lack of backlighting. Being a drawback that it shares with the Logitech K480 (which we’ve covered in our Logitech K480 Bluetooth Multidevice keyboard review), it might be challenging to use in low light conditions. They were also dissatisfied with its lack of programmable keys and missing wrist rest.