Laptop graphics have always been something of a joke performance wise. Nvidia and AMD do try, but cramming all those millions of transistors into a low-power, compact package just leads to massive expense and an inability to upgrade.

Wouldn't it be perfect if you could simply use a standard external graphics card to power your laptop's 3D graphics?

The good news is that you can. The suitably technical-sounding PE4H is just that; a passive PCI-e x16 to x1 adaptor, which enables you to plug an external graphics card into a laptop's ExpressCard slot. Currently we're only aware of it being available from the Taiwanese firm www.hwtools.net for around $100 including shipping.

We'd like to say it's as simple as that, but this project does have a few sticking points. The first we've already mentioned: a laptop with an ExpressCard slot.

The second is Windows 7, as it handles multiple display drivers far more adeptly than anything else. We're told Windows XP is next best with Vista being least desirable.

Also if your laptop has more than 2GB of memory a 64-bit installation is also required, as otherwise you'll hit the 4GB address space limit hard. The big issue here is that it'll cause the allocation of memory for the graphics card to fail.

Even though the card has its own memory the processor still needs to be able to address it, this address space is added on top of any existing system memory plus any other hardware resources, including the integrated graphics memory space.

The final sticking point is that there are certain laptop models that this simply won't work with or have some serious documented issues. Some of these can be worked around and others cannot, but before you run off and spend your money it's best to check if people have reported issues with your model.

The best two sources for compatibility can be found on the Notebook Review forum and Village Tronic. The former is the best, offering detailed system configuration and how many issues are solved.

The PE4H comes with the adaptor itself, an ExpressCard, data cable, Molex power cable and ATX power switch. Alongside this you'll need a suitable power supply, the adaptor can take a 12 to 15v supply but for higher-end cards you'll need a desktop PSU anyway. Plus for neatness we're going to house it all inside a mini-barebones case.

PE4H

The walkthrough below details putting together a system. The main thing to be aware of is before plugging the ExpressCard into the laptop, you will need to have Windows fully booted and to have the graphics card powered up. It's important to do this so Windows can recognise and install the correct drivers. If everything goes smoothly you'll have multi-card, multi-monitor system, where there was none before.

This might not be evident but it has happened, check the Display Properties Control Panel to see if the new display is detected and active.

Troubleshooting

In our case we encountered a couple of issues on our Lenovo X200 at this stage, which we can see other people encountering. If the card isn't detected reboot and see how the BIOS handles the new device.

For us booting produced a stream of POST errors complaining about PCI resource allocation problems. A BIOS update later and we had a booting system but one that was running incredibly slowly.

Our next step was to try inserting the card immediately after pressing the power button and that seemed to sort this out. Similarly another trick is to put the laptop to sleep insert the card and power back up. Whatever voodoo cured the problem, once it was up and running we didn't have any further problems and the device could be happily hot swapped. All of these issues are connected to allocation of the PCI address space for the card.

Once it's up and running it just works, albeit within the limitations of a x1 PCI-e system. You may have spotted that the adaptor card offers four PCI-e connections, the obvious question is how do you connect those additional PCI-e lanes?

Most laptops use a mini-PCI-e add-in card for its wireless adaptor, other laptops actually have spare mini-PCI-e ports for 3G modems and the like. If you can locate one of these and add-in one of the HWTool PM3N mini-PCI-e adaptors, then it's possible to upgrade to an x2 system where the performance hit narrows to around 75 percent of the graphic card's full performance.

This, of course, requires a second cable to be trailed from the laptop to the adaptor, as it turns out these are mini HDMI (Type-C) cables, so can be picked up from various sources such as www.lindy.com.

Use something like SiSoft Sandra to see what chipset your laptop has and what devices are attached to them, the Hardware Buses report tool is best. The older ICH6/7M Southbridge can provide up to four PCI-e ports. The newer ICH8/9M and HM55 chipsets can go to six, with the latest HM/QM/QS57 range providing up to eight. You need to use the ports in matched pairs for it to work, so ports one and two or three and four.

DIY desktop graphics for your notebook

We remember getting excited about an Asus prototype called the XG Station a few years back at Computex in Taipei. That device promised to do something similar to this project. It never made it to the UK though, but did pop up in Australia in 2008 before promptly disappearing within a year.

No matter, we'll show you how to hook up your own spare PCI-e graphics card to your laptop. It just takes the right bits of hardware and an ExpressCard equipped laptop. We're even going to look at an easy way to package the whole lot into an external case.

1. The kit you will need to make your adaptor

step 1

The catchy named PE4H from www.hwtools.net comes with a x16 PCI-e adaptor, the ExpressCard interface, an ATX power switch, plus the necessary Molex power cable and PCI Express data cable.

2. Grab a passive PCI Express adaptor

step 2

The adaptor that takes the PCI Express graphics card is called a passive adaptor, which is actually not doing any processing or routing, it's simply connecting two buses together.

3. Connect the GPU to the ExpressCard

step 3

Getting started is easy enough, plug the graphics card into the adaptor and connect the data cable to the first PCI-e port and to the ExpressCard, not forgetting the power cable.

4. Get a PSU powering your graphics card

step 4

So you can use a standard PC system power supply for your graphics card an ATX power adaptor is supplied, which will attach to the 20/24-pin power cable of the PSU.

5. Everything hooked up and ready to go

step 5

With a basic PCI Express graphics card the set-up looks a little like this (with or without a loop in the cable). At this point you don't want to connect the ExpressCard but you can boot your laptop.

6. Now, power up the pixel pusher

step 6

Before you go ahead and connect the ExpressCard to your laptop, you must make sure that the graphics card is powered up, so turn on the ATX switch and power up the PSU.

7. Get in on some ExpressCard action

step 7

With your Windows OS laptop up and running along with external graphics card, you can now safely push the ExpressCard into its slot, being careful not to knock over the graphics card in the process!

8. Displays ahoy, as far as the eye can see

step 8

If you have a compatible laptop, then after a flicker or two and perhaps a reboot, the laptop should detect the new graphics card and automatically start installing the driver.

9. Control, multimonitor is a go

step 9

If everything has worked correctly then you will now have a multimonitor system that you can configure from the Windows Display Control Panel.

10. Put her safe 'n' sound in the mini

step 10

To create a neat external box, we're going to cheat a little and just shanghai this rather nice mini barebones box. We won't need the original mobo though we might be able to use the PSU.

11. Compact and decidely bijou

step 11

This box has space for two PCI cards, so even a double-width graphics card should easily fit inside the chassis and the PCI-e adaptor sits nicely, where the mobo used to be.

12. Get the power that you really need

step 12

It's important to make sure the power supply unit's 12v rail will meet the power supply needs of the card. Check the Wikipedia entry to look up the TDP of your chipset if you're unsure.

13. Get a cable, that is Type C

step 13

We're going to route the connecting cable out of the side of the case. To make life easier it'd be best to pick up a longer mini HDMI (Type-C) cable, which is actually what the cable is.

14. Connect up the power button

step 14

The ATX PSU is activated by connecting pins 14 and 15 (20-pin) or 16 and 17 (24-pin) together. It's the green wire and any black wire, so you could connect up the case's power switch instead.

15. And this is one I made earlier…

step 15

And here she is, our neatly finished solution for getting desktop graphics on your weedy laptop. The mini-case, as it turns out, makes quite a handy monitor stand. Or you can just hide it away.

------------------------------------------------------------------------------------------------------

First published in PC Format Issue 247

Liked this? Then check out 15 best graphics cards in the world today

Sign up for TechRadar's free Weird Week in Tech newsletter
Get the oddest tech stories of the week, plus the most popular news and reviews delivered straight to your inbox. Sign up at http://www.techradar.com/register

Follow TechRadar on Twitter * Find us on Facebook