Building my Gaming Laptop - What do GPUs depend on for compatibility?

Hey guys, after basically teaching myself how to completely disassemble and reassemble laptops by upgrading my Dell e1505 like crazy, I'm finally considering trying to build a new laptop (mostly for a better GPU).

I've basically Frankenstein'd my old e1505, packing in the most power I could over the years. I even replaced the GPU with the only other card compatible; the ATI x1400. As you can imagine, today's games are getting to be too much to handle, though.

Here's my question(s): While upgrading my e1505 last year, I ended up buying a couple non-working e1505's to salvage parts from. I basically took the best components from all three laptops and combined them (even including the LCD screen from one). This stuff really doesn't seem that hard once you get the hang of it, soooo....

I'm thinking that I'd be able to do something similar with a newer laptop; one that has a motherboard/CPU that will support a modern-day, mobile GPU. The thing is, I don't know how to find out what the limitations are, and what the variables are...For example, if you have the right motherboard, does it sometimes come down to just being able to physically fit the graphics card inside, with the way the components are spatially designed?

I've looked all around the Internet at "DIY Laptop" and "Build a Bare-Bones" sites, but most of them are a few years old...Wouldn't I be able to do something similar to what I did with my Dell e1505, like buying a dirt-cheap starter notebook from Dell or another manufacturer (assuming the "choose your upgrades" page for that model lists a high-end GPU as a choice)? Or even buy a non-working "shell" notebook from eBay or something, and slowly collect used and new parts to build it? Judging by everything I did to my e1505, it seems like this would work, as long as you knew which hardware components were compatible with each other.

Does anyone have any advice about this? Right now, the main thing I'm confused about is "GPU barrier." I'm trying to figure out, for example, what the variable is when you buy a laptop online from a manufacturer that lets you "upgrade" your GPU by adding X amount of dollars...Regardless of the manufacturer, most laptop models sold online give you a choice of higher-end GPUs, and I'm trying to figure out if those CHOICES are dependent on the motherboard/CPU in the laptop, or if it's something else.

Lastly, to summarize I guess;

1) What's to stop me from searching manufacturers' websites (like Dell, Asus, etc), finding a specific laptop model that's offered with the option of a high-end GPU, then looking on eBay or whatever for a non-working version of that same model, or even a shell (basically just the case and motherboard), then gradually buying new and used parts to build it?

2) When it comes down to it, what is the main factor that defines whether or not a mobile GPU is compatible with a laptop? I'm not talking about the manufacturer; I know that most of the time it would be impossible to mix one manufacturer's GPU with another manufacturer's laptop. But assuming I go with one manufacturer, and I pick a modern or semi-modern laptop model, and the manufacturer's "choose your hardware upgrades" page for that model includes a high-end GPU as a possible choice...what's the variable? Is it the motherboard/CPU? What does the compatibility depend on?

If you stuck with me this far, thanks for reading this wall of text. If I had more formal training in hardware, I probably could have asked this stuff in one paragraph.

Thanks,

Josh

 

There are several variables, even when dealing with the same vendor's motehrboard/GPU combinations.

The first is the card type. Several vendors use MXM, but there are different versions of the MXM. Current high-end GPUs are MXM 3, while the last generation used MXM 2.1. You have to have the right version for the laptop, and some systems use proprietary systems, or non-standard MXM types...for instance, Asus uses MXM, but the cards are reversed from the typical MXM so that they only fit another Asus.

The next major problem with compatibility is cooling. Even if the GPU is the same card type, it may require a different heatpipe.

The last problem is the motherboard chipset, which may limit support for GPUs, especially if you want to switch between ATI and Nvidia cards.

The only way to really be sure is to stick to combinations that the manufacturer offered for that model.

 

Your best bet is to start with a barebones laptop and go from there. That way you can install your own CPU/GPU/RAM/HD, etc.. That's about as customizable as you can get with a laptop.

KimoT laid it out pretty well, for the GPU you need to be concerned about card type, chipset and cooling. The first two are pretty easy to nail down, but cooling is tough, and arguably the most important. You can very easily frankenstein yourself a new laptop only to have it melt down on you a few days later.