Desktops

Desktop sizes from full tower to all-in-one:

size decides almost everything else about a desktop. A full tower has room for a long graphics card, extra drives and big coolers, which is why gaming and editing machines are built in one. Small form factor boxes such as the Dell OptiPlex or HP EliteDesk SFF take a slim low-profile card at most, and palm-sized minis such as Lenovo’s ThinkCentre Tiny or the Mac mini take none at all. In exchange they are nearly silent and screw onto the back of a monitor. An all-in-one puts the computer inside the screen: one cable and a tidy desk, but the hardest machine of the lot to fix or upgrade. If the machine has to travel with you, laptops are the better place to start.

Branded office desktops against a home-built PC:

the other split is how the machine was put together. An office desktop from Dell, HP or Lenovo is dependable, but often comes with its own motherboard shape and a power supply on a connector no standard unit fits, so turning it into a gaming PC later means replacing far more than the graphics card. A PC assembled from standard parts by a technician or its owner can be repaired and upgraded piece by piece, and anything from computer components will fit as long as the socket and memory type match. For games, that is the one that leaves somewhere to go next.

Why a used all-in-one loses its value:

a new all-in-one from HP or Lenovo starts at around $550 in Panama, and the better-equipped ones climb past $900. Used, it falls further than a tower of the same age, because the screen is the computer: a cracked panel or a failed backlight writes off the whole machine. At the other end, small office desktops several generations old, released in batches when a company renews its fleet, change hands at around $130 to $200 with an SSD fitted, about the least a working Windows desk machine costs.

A used desktop with the side panel off:

ask for a photo of the inside. Fans caked in grey dust mean the machine has been running hot, and a processor whose thermal paste has dried out slows itself down under load or switches off. Then confirm what is inside. Task Manager’s performance tab shows the processor, memory and graphics, and they should match the listing, because a tower sold as a gaming PC sometimes lacks the card the title promised. CrystalDiskInfo shows whether the drive reports good health or caution. Look at the activation page in Settings as well: office machines carry their Windows licence in the firmware, while a home-built PC may be running a copy nobody paid for. If the clock or the BIOS settings reset every time it is unplugged, the coin battery on the motherboard is flat, a cheap fix but a sign it sat unused for months. Check an all-in-one’s screen on white and black backgrounds for lines and dark patches, and make sure a mini PC comes with its own power brick, since the plug is specific to the model.

Listing a CPU on its own or the whole desk setup:

say plainly whether you are selling the tower alone or the set with monitor, keyboard and mouse, and photograph exactly what goes. Give the processor and its generation, the memory, the drive type and size, and the graphics card if there is one, with a screenshot of the system information screen. Before the handover, sign out of your Microsoft or Apple account and reset the machine with everything removed. A tower heading home from Juan Díaz in the back of a taxi rides lying flat with the side panel up, so take out a heavy graphics card first or warn the buyer it is still in there, and keep the box for an all-in-one: its screen is the part that cannot take a knock.