The hard disk, the fan, the CD-drive.
More difficult to trace, the inverters.
See this picture of the mobo top: http://www.rkawakami.net/ibm_t2x/mobo_top_72_legend.jpg
- big rectangular above left of the CPU (at location A1/A2, but it's missing on this picture)
- square 'blob' at C5/C6 and G6
And on the bottom: http://www.rkawakami.net/ibm_t2x/mobo_b ... legend.jpg
- square 'blob' at D9 and E8
These last two have a nasty habit of sometimes falling off due to bad solder joints.
If you have the mobo out, just try to 'lift' them off putting a fingernail under it.
If they do, scrape the metal contacts and the matching solder points on the mobo and solder them back on (either way is fine).
Don't mix them up, they have different values.