What is worth taking into account is that PC's use the earth (cpc) of a circuit to "dump" the kinetic power they accumulate. I could probably find out the finer details of why but for now just take it as a given that they do. If you assume that one PC will discharge between 0.85 to 1mA a circuit with approx 30 PC's is going to trigger the RCBO. I found that out by insisting all sockets should be RCD protected and had to deal with this issue. So if you are also satisfied that the floor boxes are to be used solely for the purpose of powering PC's that should be floor boxes covered.
Usually in an office the other items of equipment that office staff plug in are mobile phone chargers, fans in the summer and heaters in the winter. The regs state that a suitable risk assessment and method statement should be in place where sockets with no RCD protection can be used by those not instructed to
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One thing that is very important to remember though is to see if all the socket outlets on the Distribution Board you are working on are on the same phase. Who knows when an extension lead may find itself close to another outlet that's on a different phase giving you a potential 415 volt accident.
Cleaners sockets, Kitchenette areas and others for example dado trunking I would protect as you could assume these are to be considered for general use.
For essential supplies such as servers, you can cover yourself in a number of ways where RCD protection may give you nuisance tripping. These being Labeled "Server Equipment Only NO RCD PROTECTION", change the outlet to a commando socket or as the regs state permanently connected items should be supplied from a fused connection unit and not exceed 20A.
Whats stopping you from installing a new circuit? If its not practical to protect the whole circuit with an RCBO you could protect those that you deem to pose a risk with an outlet with RCD protection included.
I always look at any scenario with the view of If I'm unhappy with it and its dangerous, make it safe by isolating the supply. Highlight the issue to the owner of the installation and document the fact, Then its up to them.