Upgrade old alienware m11x from core 2 to i7?

This has been asked before - the answer is no.  The CPUs in this model are soldered to the mainboard, and if you look at the chassis of the two systems, the port arrangements are different - meaning you'd need the board with its soldered-in CPU plus a whole new chassis.  Even if you can find a board/CPU and the chassis parts, the cost will exceed that of selling your existing system and buying a new one - not to mention the fact that you'll get only a 90-day parts warranty at best on the part-build approach.

I think you should look at this thread.

There it's told that the SU7300 CPU ISN'T SOLDERED!! It's even a guy from dell who tells it, and this other guy is asking if he could upgrade to a SU9600, which is the same processor as the SU7300 just with 2.0 Ghz.

Can you please explain this?

There are two versions of the M11x - the R1 and R2.  The R1 units had soldered-in CPUs.  The R2 versions don't.

The post I answered some time ago asked about the original M11x - which does have a soldered-in CPU.  It cannot be upgraded.

There is NO WAY to upgrade any Core2 system to a Core i.  The mainboards are different, and if you look at the layouts in the service manual, the one from the i7 will not fit the older case (and vice-versa) because the port layouts differ dramatically.

Unless you know for a fact that Alienware shipped the model you have with that CPU, it's a very risky buy, and as noted - you must have the R2 -- NOT the R1 referred to in the original post.  Those DO have BGA (soldered) CPUs.

I understand that it is impossibly upgrading to a icore, but what i'm asking, is it possibly to upgrade to a bigger core 2. From a SU7300 to a SU9400 or SU9600 with the same chipset. Like in the thread i gave you the link for.

But then I break the warranty, but how can you even see that the warranty is broken if I can open my computer, take out the parts, and put it back together without a scratch? Because if the warranty wasn't there i had opened it up long time ago.

But does the R2 models only come with the icore CPU's and not the core 2? and the R1 only comes with the Core 2 and not the icore, or am I totally wrong?

Unless you have evidence otherwise, which I'd be curious to see, my understanding is that Intel never released the SU Core 2 in anything other than micro-BGA 956 format - these CPUs are ALL soldered.

If you already have the system and need definitive convincing, remove the keyboard and take a look.   That will answer the question beyond a shadow of a doubt.

If you're going to upgrade the CPU, THAT will void the warranty anyway.  In any case, unless you can find a non-BGA SU Core 2, you're out of luck.  There aren't any.

The CPU in your system IS hard soldered to the mainboard and it is not upgradeable.