One of the selling points for thin clients is that they last a long time, but you can't hold onto them forever...
Unlike PCs with a lot of moving parts and hardware specifications that change fast, a thin client is a fairly basic device with a slower rate of obsolescence. Still, all good things come to an end eventually, and even a thin client needs to be replaced at some point.
So what are the triggers for thin client retirement? Support, features and performance are the usual reasons; simple old age is seldom the issue with thin client terminals as it is with PCs.
Development, performance lead to retirement
One trigger is when the vendor stops developing the terminal. I recently saw one customer with thin client terminals that were five years old, and the vendor had stopped developing them two years before. The latest version of the VDI software that is supported with these clients is now two years old, so if the customer wants to use features from the newer software versions, the thin clients need to be replaced. Still, keep in mind that these terminals haven't even been power cycled in three years -- try that with a PC.
An even more extreme vendor support issue is when the vendor goes out of business, as happened to customers of Pano Logic. When there's no availability of new thin clients and doubts over the long-term support for existing clients, customers should be evaluating new ones.
This situation also highlights the importance of selecting a thin client vendor that is well suited to your organization. Small vendors often have lower unit prices and innovative features, and they may suit more agile customers. Larger vendors may only deal with large numbers of devices and aren't so fast to adopt new features, but they have long support lives for their thin client terminals -- making them attractive to enterprise customers.
Another reason to update your thin clients is if you require better graphics performance. A thin client that was deployed to support Office 2003 on Windows XP may simply be unable to move enough pixels around on the screen to cope with graphically rich applications. Newer thin clients have had the benefits of CPU development and often contain a GPU to handle these more demanding apps.
Considerations when replacing thin clients
More on thin client terminals
How thin clients reduce management headaches
Going through today's end-user devices
Comparing thin clients with zero clients
Changing VDI products or moving from Terminal Services to VDI often means a new display protocol. Since many thin clients are very limited in their protocol support, a new VDI platform could mean a need for new thin clients. A four year old thin client won't support new Citrix HDX features or protocol enhancements such as Microsoft's RemoteFX.
I have a thin client on my desk that is great for Citrix connectivity. It was ideal when I bought it, but now that I mostly work with another vendor's products, the terminal is less useful. Sometimes buying a more expensive but more flexible thin client is the right choice, rather than risk needing to replace them all when products or needs change.
Age doesn't usually bring the need to replace thin client terminals. With no moving parts and no build-up of installed software, the performance of a thin client is uniform across its life. The final test to determine whether a thin client is still fit for the job is if it allows your users to do their jobs and doesn't cost you a lot to support it.
If for the first time in five years, IT has to visit every desk and put new hardware in place, your thin client has lived a long and valuable life. Just remember, no matter the reason for retiring and replacing your thin clients, it is a big job. New thin clients often mean new management tools and processes.