I know this laptop is quite old, but it always had that problem but only now I'm reporting it. I have to say that I have searched everywhere (on google and in this forum for a similar problem/solution) but I couldn't find anything (my apologies if there's instead, it would be great if you could point me out in that direction).
In few words, the laptop randomly freezes, with no reasons apparently (even now while I'm writing this out, it did it 3 times). While freeze, everything including audio, video, the PC in general is completely unresponsive (if I'm watching something, both video and audio stop with the audio making noise like skipping forward and backward. Not sure how to describe this, English is not my first language). Keyboard and touch both unresponsive, etc.
it lasts few seconds, I would say 5 or 6 and this does happen in a randomly way, not every 30 mins or 10 or 20. it could be 4times in an hour, then 0 next hour etc.
Your laptop is over 7 years old (maybe 9 years, hard to tell from Dell's documentation). The thermal compound has dried out and is not adequately transferring heat away from the processor, and there may be a lot of dust inside the laptop and maybe inside the fan and heat fins. So, your laptop is unable to adequately cool itself.
Perform an internal cleaning. Open it up to clean out dust. Disassemble the fan to clean out dust and fluff. I found a fair bit in two laptops I worked on recently. Remove the heat sink, remove the old thermal compound and apply new thermal compound before reinstalling the heat sink.
While you're in there, replace the CMOS battery. If it isn't dead, it soon will be. BIOS settings and date/time can't be saved without a functioning CMOS battery.
Follow the disassembly and reassembly steps in Dell's manual. Look on YouTube for videos showing disassembly of your model. But, be cautious with them, as some use steps or methods that are not appropriate. Use the videos to add to your understanding of what to do, but follow the steps in Dell's manual.
Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. I know many people do such work without this, but it's a cheap and sensible precaution.
You might also want to do what I did: I took a strip of lumber, about 3.5 cm. wide x 2 cm. high (1.5" x 3/4"}, and the length equal to the width of my laptop. I routed out two notches to accommodate the laptop's rear feet. The rear of the laptop sits in those notches, propping up the rear by 2 cm. That provides better ventilation underneath the laptop and makes it easier for the fan to draw in air via the bottom vent.
You can also reduce heat caused by Turbo Boost by changing power settings. Settings | System | Power & Sleep | Additional power settings | select your plan | Change plan settings | Change advanced power settings | Processor power management | Maximum processor state: set to 99% or lower. If you set it to anything below 100%, Turbo Boost will not activate, so system will not generate as much heat and you will save battery power.