Lenovo C225 All-In-One - Manual (Page 23)

c. Memory modules
d. Extended video memory
e. External Cache
f. External Cache RAM
g. Hard disk drive
h. Diskette drive
3. Power-on the computer to re-test the system.
4. Repeat steps 1 through 3 until you find the failing device or adapter.
If all devices and adapters have been removed, and the problem continues, replace the system board.
Chapter 6 . Symptom-to-FRU Index 19