What should I use to protect my PC from power problems?

Start with the outlet and wiring before buying a box to plug into it. An outlet tester can catch some common wiring faults, but it won't find every problem. If it reports a fault, or you suspect a voltage issue, have a qualified electrician check the circuit.

Multiple failures in one room are a reason to investigate, not proof that the power caused them. A surge protector won't fix a faulty outlet.

A UPS is useful if you also want time to save your work and shut down during an outage. Look for one with automatic voltage regulation and surge protection if those are concerns. A surge protector alone won't keep the PC running when the power goes out.

Check both the VA and watt ratings, especially the watt limit. Add up the expected draw of everything you plan to connect to the battery-backed outlets, including the monitor, and leave some headroom. Runtime depends on the load, so check the manufacturer's runtime estimates rather than assuming a particular number of minutes.

For a tighter budget, a reputable surge protector is a reasonable starting point. It handles surges, but it doesn't provide backup power or necessarily correct sustained low or high voltage. A separate automatic voltage regulator is another option, although the price may get close enough to a UPS that it's worth comparing them.

Don't overlook the PC's power supply itself. Its rated wattage and efficiency label aren't the whole story, and component failures can have causes unrelated to incoming power. Check the PSU model and its condition as part of troubleshooting rather than assuming a new surge device will solve it.

If you choose a UPS, check compatibility with the PSU. Some active PFC power supplies can be sensitive to simulated sine wave output on battery, so a pure sine wave model is worth considering.