Buying a used computer CPU

November 5th, 2011

CPUA CPU is one of the most important parts of your computer system. It’s like the brain of a computer system and is responsible for most of the data processing. As a result it plays a major part in a computer system’s performance.

Buying a used CPU can lead to significant savings at minimal risk. New CPUs are released all the time so older models can be had at a good discount. A second-hand CPU is the most risk free purchase of used computer hardware you can make. This is because a CPU either works perfectly or not at all so it’s easy to tell what condition it is in. If it works at all then it’ll continue to work happily for decades. If it doesn’t work then it’s dead and worthless. There is no room for doubt. However, there are certain steps you can take to ensure that you purchase a fully functioning CPU:

  • First take the CPU out of its socket and examine it closely. Look at the top of the CPU where heatsink is. It should be free of any burn marks or other obvious signs of damage. The top of the CPU will likely have thermal paste on it so removing that thermal paste maybe required. You can use rubbing alcohol to do that. Obviously don’t use water.
  • Take a good look at the underside of the CPU. If it’s a pinless chip make sure that all the contacts are in good condition. There should not be any foreign matter covering them. Foreign matter covering the contacts can cause short circuits and even cause the CPU to burn. If the CPU has pins then make sure that all the pins are present and fully upright. Bent pins can cause short circuits. Broken pins can cause a CPU to malfunction.
  • See the CPU in action. The seller must have a motherboard, RAM, PSU etc. so that you can install the CPU and see it functioning in a working system. When booting up the system be sure to go into the BIOS menu to verify that the CPU is the correct model. Also make sure the system boots the operating system successfully.
  • If possible run a CPU stress test like prime95 for a few minutes. Using a CPU temperature monitoring software like real temp you can see whether the CPU runs within the manufacturer’s prescribed temperature limits when under load. If it doesn’t you may have to reapply the thermal paste and reseat the heatsink fan.

The rule of thumb is that you have to reapply thermal paste every time you remove the Heatsink Fan or HSF assembly from top of the CPU. So once you’ve bought a used CPU you will need to reapply thermal paste. You can buy cheap thermal paste in large computer shops locally. Small shopkeepers will not know anything about thermal paste so avoid asking them. Before applying the new paste you will have to remove the old paste from the bottom of the HSF and the top of the CPU using alcohol swabs purchased from a pharmacy. Then you install the CPU in its socket on the motherboard,  apply a tiny amount of the new paste onto the top of the CPU and install the HSF.

Buying a used CPU can save you quite a bit of money and following the steps above ensures that you get a working chip.

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One Response to “Buying a used computer CPU”

  1. kashif says:

    very interesting information about computer hardware. good effort…..

    Posted on 26 Dec 2011 Reply

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