Of all the thousands of individual different types, of desktop computers out there, I have never run into this one before.
(Not like I AM going to know about each, and everyone one of them, lol; but I have been around at this for years)
Looking at the Specifications on HP Support, and individual reviews on the internet; I see it uses a small external power supply.
Rated at a maximum Wattage of 65 Watts, and resembles a laptop power supply.
(I can't seem to pull up the power supply itself, to have a look at it)
If this holds true it probably does not have a switch on it, to switch from one incoming AC voltage, to another.
That is to say, 120 Volts, or 240 Volts.
If like a laptop AC adapter, it automatically sets itself to the incoming AC voltage; from your home, or place of business.
Uses the PFC technology; Power Factor Control,http://www.hardwaresecrets.com/article/Anatomy-of-Switching-Power-Supplies/327/2http://www.hardwaresecrets.com/article/Anatomy-of-Switching-Power-Supplies/327/6
Obviously the article is for a Switched-Mode Power Supply, as used in a desktop computer. (SMPS)
But the PFC information they give, also applies to a laptop type power supply. (AC adapter. Commonly known as a 'Charger')
On the label sticker for the power supply, it should state;
Input: AC @100 ~ 240V
Alternating Current at 100 to 240 Volts.
IF not, then there may be a Slide switch, or a Rocker switch.
IMHO there will be no switch.
May I ask what the problem is?
Moved from one country to another?
All you should need, is a type of adapter plug; to go onto the plug of the power supply, so you can plug it into a surge protector.
Or plug the power supply into a surge protector it fits, and use the plug adapter for the surge protector's power cord.
Post back in a Comment, Anita.
"The Pieces Included........"