When speakers are connected to the computer, they produce a popping sound every second. However, when headphones are connected to the speakers the sound works fine.

Monitors seldom have sound. This one of yours is little known as I am trying to find the specs on it. Sometimes they have an audio socket, but you have to run a cable to powered speakers. The data signal from a computer sound card is not amplified, it is just data.

https://www.google.com/search?q=CMV+CT-723A+specs

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These are analog speakers and do not need a driver. First, make sure they're plugged into the speaker/headphone jack and not the microphone jack. Second, make sure the computer's sound output is enabled and set the headphone/speaker jack. Third, verify that the sound output is working by plugging in a headphone set or a different pair of speakers. If the computer sound checks out, the speaker cable is bad or the power supply is not working.

It certainly seems the power amplifier is faulty.

I assume you are using the headphone jack on the HP? You do know they need powering from the USB port? First try headphones and see if they work, then unplug speakers but leave the USB cable in and turn up volume to full and tap the end of the audio plug. Can you hear a click from the loudspeakers? report back

Few things.
If you are talking about the built in speakers, make sure your volume is turned up. And make sure its turned up when the headphones are not plugged in. My android tablet has individual sound profiles so while I might have the sound muted when the headphones are not plugged in, if I plug them in, the volume jumps to my set level because that's where I turned the volume up to last time the headphones were plugged in. I've also had two tablets that the speakers went out completely on that to is a possibility but if you are talking about the built in speakers, check the volume levels first. You can get to them in the settings menu. Its worth noting that plugging anything into the headphone jack will "turn off" the internal speakers altogether.

If you are talking about external, plug into the jack speakers, on a tablet, you're going to need a set of powered speakers as that jack is not going to produce enough power to drive an un-amplified speaker. Make sure you are using a pair of speaks that plug into the wall such as PC speakers.

Second, if you are using powered speakers and still not getting any where, look at the jack end of your head phones and compare it to the jack end of your speakers. I know iPhones and other Apple devices have an extra connect which is why the Apple head phones all have an extra ring. My older headphones are worthless in my iPhone because they lack said extra connection. It's possible your tablet also requires the newer connection and the headphones have that while your speakers don't.

Broad answers, but I couldn't tell exactly what we were looking at based on the questions. Hope it helps, and good luck!

Try a pair of headphones. If you can't hear any sound it's not the speakers. If you can hear sound, it still might not be the speakers. As sometimes headphone sockets which cut the speakers off when headphones are plugged in, can go faulty. To test any loudspeaker connect a 1.5 volt battery accross it's terminals for a few seconds. It should POP.

Check your system if you are able to hear sound using any headphone..if you are able to hear sound from headphone then the problem is with your dell speakers,else you need to update sound drivers for your system...Thanks..

Do the speakers have power? Check the fuse.

Where are you plugging your headphones?
Where are the speakers connected? Is it the same jack as the headphones?

Have you tried plugging the speakers into the headphone jack vs the soundcard?

from what I've read, the imac has a 3.5mm (.138) jack while the Bose jack is 1/8 (.125). very small difference in size (.013), but enough to cause problems.

i had the first problem and you can probably fix it by turning the volume knob all the way up and down about 20 times. it worked for me. supposedly the potentiometers in the z-5300 get dirty or worn out, somehow this might fix it. for the second problem maybe try plugging it into the laptop and unplugging it again seeing if it goes back to normal?maybe its a problem with the amp?