Lenovo ThinkCentre E73 Hardware Maintenance Manual page 70

d. Extended video memory
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 109 or "Replacing the system board" on page 159.
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ThinkCentre E73 Hardware Maintenance Manual