Is it possible to install a discrete mobility card on a laptop without a graphics card already?

To be specific:

Can I:

1. Install a discrete graphics card on a laptop that does not come with a discrete graphics card?
2. Teach windows 8 to use the discrete card over the integrated graphics?

To me this is the only downside of my laptop and I would not mind getting any graphics card as long as it is better than the integrated laptop card (an Intel 3000)

The laptop if you need more information is an Asus U46E-BAL6.

Graphics chips usually reside in one of three places:

1. On the motherboard.
2. In the CPU / APU
3. On a dedicated graphics card.

1)
On most older laptops you will find the graphics build onto the motherboard. Replacing those usually comes down to replacing the entire motherboard. Essentially you get a new laptop in the same case. Possible with some laptop models. Usually expensive.

Consider that a no for practical purposes.

2) Many modern CPU's add a graphics core to their CPU. This is the case with your laptop. It has an Intel I5 CPU, with a graphics 3000 core. You can not replace this without replacing the entire CPU.

In your case that might be possible. Asus sells your laptop with three different CPU's: A i3 2310M, i5 2520M and a i5 2410M

If you Intels website compare these three CPU's then you will notice that they have three differently clocked graphics cores. You could replace the laptop with the fastest one sold by Asus, or you could try to use another CPU. The last would need to be supported by the BIOS; it should not use more power; it should not generate more heat.

3) A few laptops come with dedicated graphics cards connected via standardized miniPCI or miniPCIe slots. You can change these if:

• You have such a (gaming) laptop.
• And you happen to have the right card which is supported by that laptop.
• And if the laptop can power it.

The last is non trivial. Some of the gaming laptops need three(!) power bricks. (Max power per standardized laptop PSU is limited and mobile gaming cards can draw up to 100 Watt per card). Some laptops even support crossfire or SLI.

The second bullet point is more subtle: miniPCI and miniPCIe have been standardized. But many laptop do not support all devices. It seems to come down to 'do I have my own brand card 1? No? then check if I have my own brand card 2 No? FAIL TO START. Even if they technically should work.

People without regard for their hardware have worked around this by booting their laptop, and inserting a miniPCIe card after it was past POST. That falls under the heading of 'do not try this at home' and 'quite impractical to do'.

Then there are a few rare laptops with MXM. Quoting Wikipedia on that:

A Mobile PCI Express Module (MXM) is an interconnect standard for GPU's (MXM Graphics Modules) in laptops using PCI Express created by MXM-SIG. The goal was to create a non-proprietary, industry standard socket, so one could easily upgrade the graphics processor in a laptop,

It is used in some Clevo and Alienware gaming laptops.

That completes the answers to the three points I started with, namely where graphics parts normally reside. However since a few years there is a new bus on the market: thunderbolt

I see no technical reason why you could not connect any graphics card to that. It should be initialised early enough to be used by the OS.

In practice it might be a bit harder to use: For once the BIOS needs to work properly. With laptops that is not a given.

However there are external cases on the market using powerful full sized desktop GPUs connected via thunderbolt. example.

It will be interesting to get this to work, but it is not a portable solution.

(I noticed you have a laptop which design point is 'superior portability'. Still, for completeness sake...)

That leaves your second question: I do not have any experience with windows 8 yet. But I see no reason why could you not do this if you have a laptop with MXM or Thunderbolt. (Your laptop has neither of those two).

[Update 2 years later]

It is now late 2014. Thunderbolt is much more common. There are now several (expensive and bulky) external cases with a desktop PSU, a desktop type GPU and a thunderbolt connector.
Example This is still slower than native PCI-e due to increased latency and because many thunderbolt controller are only equal to PCI-e v2 x1 or x4. But it is now practically possible to add (not replace, but add) a decent graphics card to many laptop without going bankrupt.

That allows decent gaming at a home setup while keeping a mobile and energy efficient system. (Unless you want to drag around a second device roughly equal in size to a laptop and a monitor to connect to it. In that case it is 'portable').

One more thing I seem to have missed a few years ago is expresscard. Expresscard is the successor or PCMCIA and PC Card.

^{Expresscard image. Source: Wikipedia}

En expresscard slot has two important parts. One is an USB connection, the other is a single PCI-e express lane. (Which can be both PCI-e v1 and PCIe-v2). There is no additional latency, but the limited amount of space in the slot for the card means that you end up with a similar construction as with Thunderbolt and external graphics cards. Just without the PCI-e to Thunderbolt and back translation.

Example

The usual disclaimer: I do not work or profit from any of the URLs I linked to. They are just the first two links I found via a web search.