In Windows 7 and the BIOS, the power settings are pretty limited, just "active" or "passive" (you want active) unless you also want to do something extreme like not run the CPU at more than a fraction of its speed. I've been using TPFanControl
to boost the fan speed instead.
My W520 shut down while rendering H.264 video for a couple hours during our mini-heatwave this week on the east coast USA. The reported temperature climbed to 97C (ambient air was 80F) despite my efforts to keep the fan speed at max. I had customized the TPFanControl ini file to use higher fan speeds and not relinquish control to the BIOS until it hits 95C; Tmax is 100C on the i7-2820QM.
After this happened, I spent an hour or so disassembling the machine, removing the cooling unit, and replacing the goop Lenovo uses (always too much, it seems to me) with some carefully applied Artic Silver 5. The air temp had gone down a couple degrees F during this process, so the comparison isn't perfect but when I restarted the renders, the max fan speed was able to hold the die temperature to 90C +/- 1.
I mentioned in another post
can give better temperature information. It also offers graphs which could really help you determine whether your wife's W510 problem is in fact temperature related.
If she's not pushing the computer too hard and the environment isn't particularly hot, the computer shouldn't be getting hot enough to shut down. Unless you've got dust bunnies in your cooling fins or they really botched the thermal paste when they reassembled the machine.
I think your first step needs to be to confirm that the problem is cooling.