This "could" be a power supply problem though it is not the most common cause.
9f is likely a driver issue. Antivirus/antispware/security programs can also cause these issues. Have you added devices lately or updated drivers - be sure to check in Windows Updates to see if a driver was updated prior to this occurring. This could also be caused by a loose card or cable and even a weak power supply.
That error means a driver is not handling the power state properly. Check in Control Panel - Device Manager to be sure major drivers are not shut off during sleep - double click Display Adapter - NIC and WIFI - Sound and others - Power Management tab - uncheck Allow computer to turn off power. Maybe only one has an issue.
Start - type in Search box - MSCONFIG find at top - Right Click - RUN AS ADMIN
General Tab - check Diagnostic Start - APPLY / OK - REBOOT
Try it now. If it still blue screens think Video Driver. If not think NIC, Wifi, Sound, or...... (and it still could be video interacting with something else). See troubleshooter link above for my generic driver update methods.