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Introduction

If your Dell Optiplex 745 Ultra Small Form Factor has frequent system crashes, overheats, or performs poorly, the CPU may need replacing. You might also be replacing the CPU during routine maintenance or upgrades.

The CPU is a core component of the computer which provides the instructions and processing power a computer needs to function. A faulty or old CPU may cause system instability and poor performance.

Common signs of a CPU failure also occur in many other component issues, review the troubleshooting page and test other components to confirm that the defective part is the CPU.

Before beginning, ensure the computer is disconnected from a power source. Follow the Anti-Static Wrist Strap Guide to ensure vulnerable components are not damaged during the replacement process.

What you need

Step 1 Side Panel

Dell Optiplex 745 Ultra Small Form Factor CPU Replacement, Side Panel: step 1, image 1 of 1

Make sure to shut down the computer! Go to the start menu and click shutdown from the power options first
Ensure all cables, speakers and other devices are unplugged and turned off before opening the computer case.

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Step 2

Lay the computer on its side; you will see a blue knob.
Turn said knob 90 degrees counter clockwise.

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Step 3

While the knob is still turned, slide the panel case forward about 1/2 inch, and then lift the panel off the computer.

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Step 4 CPU Heat Sink

Dell Optiplex 745 Ultra Small Form Factor CPU Replacement, CPU Heat Sink: step 4, image 1 of 2

Dell Optiplex 745 Ultra Small Form Factor CPU Replacement, CPU Heat Sink: step 4, image 2 of 2

Remove the blue shield by sliding it straight upwards.

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Step 5

Dell Optiplex 745 Ultra Small Form Factor CPU Replacement: step 5, image 3 of 3

Pull back on the tab nearest to the front case fan.
Slide the CPU heat sink from under the clip and pull upward.
You may need to twist the CPU heat sink side to side to free it from the thermal paste.