Many thanks for your reply.

Do you know if Dell would cover the cost of the damage if the leaks damage the PC? (if the PC is under warranty)

Best 

In 10 years, I've only heard of that happening once-or-twice.

Yes, they would likely cover it (why do you expect they would not)?

If installed properly (and not messed with) the Asetek OEM Liquid-Cooler should work for the life of the machine.

My Alienware Aurora-R1 (circa 2010) still has it's original one and still works fine (and it's been pushed hard over the years).

@Saamkvn @Anonymous :

The title scared me for a moment. So it's just hypothetical. Take @Tesla1856 's advise. Dell warranty. Maybe do the extended too and get it in writing that it covers all damages if leak happens.

Thanks for your reply.

Many I ask whether you use liquid cooling for rendering/ gaming or machine learning?

And can do you keep you PC on overnight for many days in a row? As this is what I want to do and I feel if I do I might damage the cooler.

If you buy this Asetek pump at retail it comes with a 5 year warranty, so I'd expect at least that from the Dell AIO (which uses the Asetek pump).  

The pump operates at a single fixed speed so I wouldn't expect a large increase in wear based on type of usage. 

"Otherwise, if the unit leaks/breaks, you would replace the entire system for $80."

AIO part # from Dell, for the Aurora R5-11 ( think it's the same for all these generations), is MH0HN, $109 last I checked, but that was a year ago. 

But yeah, you could replace it with an H60 or H75. 

you said your original one has lasted for 10+ years?  Did you need to do any maintenance on it like thermal paste or new radiator fans in that time?  Thanks

My R3 since 2011 hasn't needing any maintenance or any replacement fans. I probably need to replace the thermal paste, maybe next time I am at my Nephew's place as he is borrowing it