Lenovo ThinkCentre M90 Hardware Maintenance Manual page 71

e. External Cache
f. External Cache RAM
g. Hard disk drive
h. Diskette drive
3. Turn on the power and the computer to re-test the system.
4. Repeat steps 1 through 3 until you find the failing device or adapter cards.
If all devices and adapter cards have been removed, and the problem continues, replace the system board.
See "Replacing the system board" on page 78.
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Chapter 7 Symptom-to-FRU index
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