If you are worried about supply line fluctuations, you might consider a UPS (Uninterrupted Power Supply).
A surge protector is basically a fuse, more or less, that is sacrificial. Should a large transient spike come through (such as a lightning strike) then the MOV or MOVs direct the excess current to ground. In case of a direct lightning strike, the surge protector may sacrifice itself in order to protect what's plugged into it.
It also depends on how good the electric supply is where you live. For instance, where I live, lightning is pretty rare and so little is done to prepare for a lightning strike. We don't seem to have large fluctuations in our electric supply that cause problems for electronic equipment. As a result, I don't plug things into a surge protector and have never had any failures because of it. YMMV.
Having an MOV in the PSU itself is simply extra protection. It would be able to handle a certain amount of transient voltage spikes but an external surge protector offers better protection.
A surge protector is basically a fuse, more or less, that is sacrificial. Should a large transient spike come through (such as a lightning strike) then the MOV or MOVs direct the excess current to ground. In case of a direct lightning strike, the surge protector may sacrifice itself in order to protect what's plugged into it.
It also depends on how good the electric supply is where you live. For instance, where I live, lightning is pretty rare and so little is done to prepare for a lightning strike. We don't seem to have large fluctuations in our electric supply that cause problems for electronic equipment. As a result, I don't plug things into a surge protector and have never had any failures because of it. YMMV.
Having an MOV in the PSU itself is simply extra protection. It would be able to handle a certain amount of transient voltage spikes but an external surge protector offers better protection.
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