As the title says, I have a brand new, unopened Cooler Master Seidon 240M AIO.
https://www.amazon.com/Cooler-Master-Seidon-Liquid-Cooling-x/dp/B00AZQYA0A
I bought it in a middle of 2013, iirc, and totally forgot I had it. As it happens, I do need a new cooler atm.
Or is it done for? I don’t have a lot of experience with AIO or water cooling in general.
I thought, it won’t hurt to ask, before I remove my current cooler… I’m lazy 
Can you try running it outside your case? I doubt much could be wrong with it, other than something going screwy with the fluid.
I would say no…
I got an AIO from a review site back in the day. They just reviewed it and sold it to finance another review item. It was 2 years old and it was clogged.
There are chemical reactions in the liquid, corrosion of the metals, etc etc.
It’s not a random thing, that most AIOs have 1 or 2 years warranty.
IIRC that is the improved model of the original seidon series of coolers . They had square CPU blocks and had a huge amount of complaints about leaks, dead pumps, issues and what not. The round pump seidons were the improved models, but it’s still a 6 years old…
If you want to try, plug it in and try a dry test… Let it run away from the PC, running at full speed for a day or so and look for leaks. If it’s all fine, you can mount it and check if the flow is OK…
But if it was me - I wouldn’t…
Modern CPUs run under normal voltages are unable to cause themselves damage by overheating. Worst case scenario, the CPU hits its TDP and throttles, then eventually shuts down.
My guess it won’t perform very well and you’ll want to replace it. But you might as well try.
This is why I don’t do water-cooling. High-end air offers almost the same performance and it never degrades or requires maintenance.
No… Not generally. Test it outside your case … moving water using results in less corrosion but given its just been sitting I would opt to test it to see if it is… The fluid or melts will have likely galvonically corroded
That won’t happen unless the AIO uses two different types of metal for some reason. Nah.
The most likely result is that some of the liquid evaporated through micropores in the tubes over the years, impeding performance.
No harm in testing it, as long as you aren’t overclocking (even then, meh.). If it works, it works, if not, you’ll know.
Test it outside of the case for leaks, just in case, then throw it in.
Yes I would run it for an hour outside the case on some newspaper or something just in case of leaks. Can’t be too careful.
I completely forgot to add the info on teh CPU:
It is Intel Core i7-4770S - so it’s only 65W - and I never overclock, ever.
But, yeah, it’s been 6 years, and with water - I was not sure.
Thanks for the suggestions to test it outside. Should I simply connect it to any free fan pin on a running machine?
Yep, pretty much.
FWIW, I had a Seidon 120M in a machine up until late last year. Didn’t leak. I put the stock intel cooler back on since that machine’s a server now, but I think as long as you first give that 240M a test it might actually be okay.
Just checked and I got my Seidon 120M in mid 2013.
Thank you, everyone, for you help.
Will test it, and report back, how it went.
I ran it outside the box for about 4 days - no leaks. Although I sometimes heard some sloshing sounds. It feels, like some liquid should have evaporated over these years, probably…
For the last 3 days, it’s been running inside the rig, and cooling fine. Well, for my needs, at least: 29-34 C during normal everyday stuff.
I haven’t run any stress testing. Not sure if I want to, or should I?
Like I said, this rig is not overclocked (I never do). And I don’t do anything fancy - basically internet browsing and coding. Come to think of it, I never even game anymore. I always think I will, but kinda never do 
So, thanks again for all the help and answers, guys. It seems it worked out this time 
Yes you should stress-test it at least for a couple of hours. If you don’t overclock then don’t stress-test overclocked, that’s all.