In addition to being a 'computer guy' for most of my life, I have been involved in street racing for over 20 years. This is of signifigance due to warranty simularities.
I have dealt with auto dealers trying to refuse warranty service several times. I became familar with the Magnuson-Moss Act of 1975 which applys to consumer products. In general it prohibits a company from requiring you to use thier repair service or thier parts. It also requires a company to prove that a modification caused the failure. The automotive world is familar with the Magnuson-Moss Act and its implications. It is a constant battle between those that mod new cars and the dealers/manufacturers.
I have noticed this is relatively unheardof in computer circles. I had reason to use past experiences last year when I was dealing with Averatec about a keyboard failure.
They told me at first I was going to have to pay for a new keyb because I must have spilled something into the old one. I had not spilled anything into it and ask them to provide evidence of damage due to misuse. In the next email they ignored my request for evidence and stated that they were not required to honor my warranty because I had upgraded Ram and the 'warranty' sticker was broken. In my next reply I sent them a lenghty letter detailing the Magnuson-Moss Acts protection of consumers and specifically that they could not legally require thier customers to use them for service. I also mentioned that I was probably not the first person that has run into this with them and it might make a great basis for a class action law suit. My keyb was replaced under warranty.
IMPORTANT-That said there are many things to consider before you decide you can just run out and rewire your notebook.
-First is the fact that the company has posession of your computer and you will probably not get it back until things are resolved. Even though you have the law on your side you will probably be fighting an uphill battle.
-Next is you will most likely be talking to people who have never heard of Magnuson-Moss. This means that they will have to talk to 2 people who will have to talk to 2 people until someone gets a clue or makes a decision. This could take some time in a large company.
-You will also have to deal with cause of failure. (I will use cars here as the types of relationships are easier to see in that arena)
It is most likely an impossible battle if a modified part directly interfaces with the failed part. ie- If you add a more aggressively timed cam shaft and blow the engine there is pretty much no way you can claim that under warranty. Aftermarket exhaust however does not cause your fuel pump to go out. The problem here is that if a company says your mod directly contributed to the problem you are pretty much stuck. They will do so if there is any way they can.
This is of real concern in notebook computers because they are essentially one system.
-Last but certainly not least is the issue of stickers. A company cannot legally void a warranty because a sticker is cut/removed. However there is a huge gray area and some interesting issues regarding stickers. One example is the main sticker on Viking RAM. If you remove the sticker on a RAM module you will not be able to get that RAM covered under warranty. They will refuse to fix/replace because the sticker has the information about the modules that they require for warranty replacement.
To head off the flamers I know there are work arounds as well as instances where unrelated parts can actually affect each other. I intended to address the honest people trying to get the service/parts they are due.
This post is just an FYI and stepping off point for someone willing to learn more and spend more time than me. In the future they might make dealing with these companies easier on the rest of us.
Some links for your amusement:
the FTC's guide on Warranty Law
What Kingston Technology has to say
Know your rights and expect fair service.