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Your product key must be entered when you install Windows, and can be wrong as many times as you like. Activation happens separately and later.

How many attempts are allowed to Activate a new Windows OS before it forces a phone call to MS? Over the years, I've owned many computers with XP, and like a fool, I just put the CD's into a case with little description. I did write down the Product Keys but failed to keep them with the CD's. Dumb, I know, but it happened. I want to format one laptop and install fresh, but when the Windows installation prompts for the Product Key, I have eight legitimate keys, but not certain which one fits this CD. I could try all eight to see which one works, but I've heard that after "X" number of attempts, Windows will allow no more, and I have to call MS. Do you know what is "X"?

No, I don't.

But the good news is that it probably doesn't matter, because I think you're comparing Apples and Oranges.

Having the right product key to go along with your CD isn't quite what you think it is, and on top of that, while it's a part of activation it's not the part you think it is.

Good and confused?

Let's fix that.

To begin with, product keys aren't tied to the CD in the way that you think they are. Each CD does not have its own unique key.

A product key must match the product and CD version - meaning that if the CD you have is Windows XP with SP2 pre-installed, then any product key that came with a Windows XP with SP2 CD will work.

"Those types of failures simply don't count as activation attempts."

Caveat: I'm going to assume that different production runs of the same product may use different sets of keys, so that may technically not be true. But if you pick up, say, 4 identical copies of Windows XP at the same time from the same manufacturing run, then yes - you can shuffle the product keys that came with them and use any of the keys with any of the CDs.

In fact, I often save all the keys, and discard all but one of the CDs.

Now, as soon as you have a variation in the product - say the original Windows XP without any service pack preinstalled - then the keys used for that product will likely not work with CDs of Windows XP with SP2.

Similarly, the product keys you get for OEM versions of Windows will also likely not work with CDs of their retail equivalent. Even further, I'd be shocked if the product keys for international versions of the same product were interchangable.

So as long as you make sure that the key you have is for the correct product, then it may not matter at all what CD you use.

But failure - using the wrong product key - doesn't actually affect activation.

That's for a very simple reason: an improper product key will be rejected before you even get to activation. If the product key you're using is not appropriate to the product you're installing, it'll fail as soon as you've finished typing it in and press "Next". Windows activation was never attempted and never involved.

Those types of failures simply don't count as activation attempts.

Only after entering in the correct product key and proceding further in Windows setup will activation happen.

Activation may then fail later if that key - which we know matches at least the product we're setting up - has been used at least once before. If that specific product key has been used too many times that's typically taken as a sign of piracy, for example. If it's been used on a different machine, or if the machine it's been used on changes in some fundamental ways, then activation may kick in as well.

What it takes to get to the "call Microsoft" stage is unclear, but as I said - using the wrong product key won't even let you get that far.

Article C4285 - April 28, 2010 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Jim H
May 4, 2010 10:38 AM

I had to call MS once when I installed an OS upgrade on a laptop that was once on my desktop. It immediately tripped a Call Microsoft message and I couldn't even boot up. The call went smoothly and the service rep was very nice. I was expecting a third degree. I explained what I was doing and that the software wasn't on multiple machines. It was far easier than I imagined and didn't take 5 minutes before I was up and running and the installation count was reset. There are a bunch of free utilities available that will recover product keys. I have used them before and they work fine. Enter "Product Key Recovery Utility" into a search.

May 4, 2010 1:21 PM

I own a netbook (bought in the Netherlands) with a dutch version of WinXP Home. To change this into an english version of WinXP Home I played a little bit with an US WinXP taken from the "I386" files on a Toshiba laptop hard drive. After adding SP3 I burned a CD and used it to install a fresh Windows on the netbook--using the (legal) key from the outside of the netbook. It was immediately activated by way of the internet. No problem with international keys as far as I can see.

May 4, 2010 4:48 PM

Product keys aren't tied to the CD. Not entirely so. They are in some way but I cannot determine how.

That's what I thought until an experience showed me otherwise.
The Microsoft support guy I spoke to told me they were in some way linked but he would not elaborate.
Here's what happened.
Some years ago I had to install XP Pro SP1 on five new computers. I had a carton of 10 retail boxed copies of the software, a gift from Microsoft to the not-for-profit owner. Each product was shrink wrapped and inside each box was a folder containing the CD with the product key sticker visible through more shrink wrap.
I opened all the boxes and recorded all the product keys. I opened one folder and removed the CD and used it to install the OS an all five PCs, recording each PC name against its product key. No surrises yet.
The next week I had to install to another new PC so I retrieved my trusty CD and list of product keys. When I had to enter a product key this time, the installation rejected it so I retyped it. Then I tried the 7th key on the list. Reject again. And so on. You get the picture. I rang support and said "All these keys can't be bad. What's going on?" When I told him that I had already used that CD 5 times he told me that that was the limit. I would have to get a clean CD and reinstall using that. I pleaded not to have to redo the work and he gave me a key that worked.
For later PCs I broke out a fresh CD and the faulty keys now worked fine.
I would not have believed it if it hadn't happened to me.

As I kind of alluded to in the article, I believe it's also possible that different production runs of the same product may cause the product key set to be changed. Obviously the best is to keep all of the CDs and/or disk images, but that's not always practical either. At a minimum if the CDs are bit-for-bit identical, then the product keys that came with either will work on both.

Phil C.
May 4, 2010 6:12 PM

A few years ago I acquired a used computer with Windows XP, including the installation CD. I don't know how many times it had been previously installed, but after reinstalling it several times myself, I could no longer activate over the internet, and had to phone.

Recently, I decided to reinstall yet again, and seeing as MS has discontinued XP, I wondered if they cared enough anymore to pay people to answer phones, so I tried activating over the internet. It worked. Of course, I can't be sure there wasn't some other reason, such as how long it had been since my previous reinstallation (a long time), but maybe XP users don't have to be concerned about a limited number of online activations anymore.

May 5, 2010 1:40 AM

Here is the solution:
A little work but u can do it. Check which keys the 'other seven machines' have and pick the one left out of those eight keys. So, just select the odd man out this way and bingo!

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