Corrosion inhibitors have a useful life of 18 months max. I oversaw the operation a of electrical power plant and we would sample the coolant every 3 months and send out for testing. In my entire tenure, in m not even one instance was it determined that the corrosion inhibitors were at a level which insured protection. It must be noted that these were standby generators and they were tested for two hours every quarter.
Of course they ran during power outages such as Hurricane Sandy providing power to 2000 homes and several hundred businesses. When each of the three generators cost upwards of several million dollars, the testing more than paid for itself. If there was a "install once and forget about it" corrosion inhibitor, they'd be using it on these multi million dollar school bus size engines.
On a PC cooling system, it's cheaper to just change the coolant. Unlike engines which are comprised of various metals, galvanic concerns are far less in a custom loop or OLC like EK and Swiftech units.
On the other hand, even is asked, we will not build a PC with a CLC for anyone under any circumstances. I have no corrosion concerns about an anodized aluminum on a secondary block such as a MoBo Monoblock or RAM block, but the use of such on a CPU or GPU bock simply makes no sense ... and aluminum radiators are just silly.
If you are a bit antsy about building a custom loop, if you every bought and set up a fish tank, you could certainly build a water cooling loop. It's the assembling bock to the CPU / GFX card part that deters most folks. An all-copper / bronze Swiftech (or EK) All-In One combined with GFX card pre-assembled water block from EK is piece of cake. A H240 X2 or 320 X2 will easily handle a 1070 and 7600k, and if ya want twin 1080 Tis, simply add a 2nd radiator.
3 x 120mm (all copper) All-In-One
http://www.swiftech.com/h320x2.aspx
EK 1070 w/ EEK Full cover block
https://www.newegg.com/Product/Product.aspx?Item=N82E16814127956
Adding this level of cooling will cost ya ..
An extra $75 over a premium air cooler (Noctua NH-D15 / Cryorig R1)
An extra $33 over a quality AIB 1070 (MSI Gaming X)
You'll need a pair of fittings, some coolant and 2 feet of extra tubing all of which can be had for $20.... but considering it's just $38 more than a Kraken X62 which cools just the CPU, and doesn't do that nearly as well as the Swiftech does, to my eyes, it's the proverbial no brainer.
On the downside, you don't get the built-in galvanic corrosion cell that comes free with the Kraken and all other CLCs.
https://martinsliquidlab.wordpress.com/2012/01/24/corrosion-explored/
That's what happens when corrosion inhibitors lose their effectiveness over time