One thing you need to understand is that academic environments are not like business environments, yet the stakeholders still need to find ways of generating revenues to run their activities. As such, they are often seen to act prudence.
If, in your institution, raising an issue is the mean by which you officially inform the administration of a situation, then what you are asking is what you need to focus on in your submission.
Otherwise, if the administration is already aware of the situation arising from these old computers, what you are asking is how you can make practically convincing submission.
Whichever the case, the criteria you to consider to raising an issue are the same when it comes to computers.
But, I must ask you the following questions:
1. What type of computers are these computers == IBM/IBM Clone [OR] Apple Mac?
2. What type/speed of processors do these computers use?
3. What type of video displays (monitors) do these computers use?
4. What is the memory capacity (RAM) of these computers?
5. What processes are these computers used for and what are the software used?
Answers to the above questions will give the criteria you need to consider before raising an issue. Just because a computer CPU casing or monitor looks out-of-style does not mean it is old.
But the moment a report-generation process start taking extra 5 and above hours compared to the time already known with this same process, then you might want to raise an issue. Always start with the software first if you are using a custom-built software program. Your contract developer might be able to improve the code performance of the software program.
In 2006, I worked in Belgium Company in Nigeria that used HansaWorld CRM/ERP software. A situation arose in which a report-generation process went from 1 hour to over 10 hours. I was able to re-code the report-generation routine to bring back the process to 55 minutes. The company was Promasidor Nig. Ltd.
But if you are using a fully branded software program with a closed frontend, like AutoCAD or 3dMax, then you might want to upgrade your computer systems. This might your situation being in the 'School of Architecture and Building' in your university.