Just A Theory: External GPU's

I know this that similar things have been seen and ATI is currently working on some sort of new product external GPU's.

If I was a able to acquire an external PCI Express x16 cable, then remove my current graphics module which is plugged into an PCI Express x16 slot and then run the cable out of my notebook through the a cut-out in the bottom panel and hook the other end up to, lets say a 7900 GTX. Would it work? Can it work?

My chipset:

http://www.intel.com/products/chipsets/945pm/index.htm

 

Hmmm interesting. There would have to be some mods to the BIOS for sure. Also, how long can the PCIe cable be---they have specs for the maximum length of those cables?

 

Wait, I just debunked my theory unless there is a way to find an adapter to connect the power supply to the external GPU to an outlet or something.

Unless there is a way to adapt the six pin power connector that connects to the GPU and the other end that supposed to go into a PSU into directly to a wall.

Or you can buy the GPU and PSU and hook up the GPU to the PSU for the power it needs. But then hopefully it wont try to take the power from the laptop and blow it up.

 

Ya, for sure. It definitely sounds like it would need some kind of adapter or modification. But there are docks which let you use an external card, I've used some in the past. Those are PCI Express and some can support x16 as long as the dock can supply the power. But those are designed with docking ports...something ASUS never took past the prototype stage on our S/Z96Js - But definitely check out the schematics and layout of the docks...they have the sort of power/cooling/setups you'll need to consider, though the connector would be different - and with a dock you can actually use the laptop without it - with the internal card gutted, without the external video card your laptop would now be as useful as a rock...

Still a cool idea though if it can be made to work it'd be wicked

 

The cable would have to be short...probably a foot or less. You'd also have to figure out which pins on the laptop interface correspond to which wires in the PCIx16 connection. I've thought about doing this for my B.S.EE Senior Project, but it's definitely promising.

Expensive, risky, but great idea. Especially if it works. BTW, rig it up so that your notebook card could still fit in (for those days you go on the run) and you might have a product that could sell!

 

A foot of cabling would be fine I believe.

I guess so about the pins but I think I can make that work, the part that is hard is how to get power to the GPU. Thats what im researching and trying to figure out at the moment.

True true, first I would try it by maybe using a GPU that the laptop can power itself, it would probably have to be very low end but just to see if the concept works.

I don't think so lol, getting the cable out of the notebook would probably require some case modding.

I do not plan on attempting it until I am 98% complete in my research and have found possible solutions for the issues at hand. Then I may try it, I still have alot of digging to do on Intel's site and wikipedia as well as many good searches. Im gonna try and see what I can find out!

 

Oh this is entirely possible with current technology

You have a pci x 16 board, you can connect it to a desktop 8800 gtx absolutely.

but this would be an extremely difficult project. And if you have that kind of skill fabricating computer hardware, I can think of better things you can do with your time.

The biggest roadblock the video card manufacturers put up to this is the bios. Some laptops need the bios to be in laptop for the card to post. this type would need custom rewritten bios.

Ok and others need the bios to be in the card to post. so you need to fabricate this as well

 

You`d better start from a notebook with the vBios on a modular card if you want to do this. You will also have troubles connecting the video signals. A normal graphs card runs VGA or DVI, notebook screens run on the LDO/LVDS output ussually.

And then there`s signal integrity. Forget about UTP, you need to control your impedance all the way. Think more along the lines of STP, 16 pairs of it. And that is still no promise to success.

I know there have been plans to make some kind of ePCIe or something. Not sure where they are with that right now. I do remember this requiring a dedicated driver for each PCIe lane.

 

Here's a question - if the limitation is based on power supply, and an external desktop power supply is provided for the purpose, how exactly is the power demand controlled? Specifically, does the power requirement for the GPU require communication from the PCI express cable to signal need (not to draw power itself of course), or is it entirely indepedent and based on what the card draws itself without commnunicating this to the motherboard? If so, then simply powering it externally and leaving the internal power connector unhooked should not pose a problem. But it does seem that the bios would probably be the limiting factor, although I know next to nothing of this.

Another problem would be switching between the internal and external card, depending on where you use it. Presumably you'd use the external card at home, and the internal when movign around. You'd need to splice into wires or have some prefab split signal and power cables with switches to allow this. Plus you'd need to be able to switch between drivers regularly. Mechanically it could get pretty complicated, nevermind from a ssoftware/bios perspective.

This would be an awesome project. I'd seriously considering picking up a used sager or asus system to try this on, as I suspect they'd be a bit moe amendable to this kind of modification.

 

Switching 2.5Ghz? Good luck with that.

 

The hardware side is doable. In fact, it has been done before, as I've indicated in this thread a couple of months ago. The basic idea is to let your external GPU communicate via the extended PCIe cable, and let its VGA output go into an LVDS converter board which will translate the signals for display on your laptop LCD. Again, it's doable, especially if you have some electrical engineering experience.

The software side is a little more complicated, you will need some way of switching between your onboard GPU and the external GPU. I'd be interested if someone could tell me how the Asus XG achieves this.

 

I tot XG can only display on external monitors...

 

Well I think to be able to connect the PCI-E x16 cable you would need to remove the current onboard graphics module.

With that said as mentioned, who knows what would happen if it needed a custom written bios.

As for the BIOS I dont know what would be so hard about modifying that if you had the correct expertise.

The underlying issue here is the PSU.

 

Yes, but the purpose of the VGA--->LVDS conversion is to allow hardware like the Asus XG to display directly to the laptop LCD. If you read the post carefully, you'll see how it's achieved. Keep in mind the XG is PCIe x1, while the setup in usapatriot's idea is PCIe x16.

 

There has to be some way of getting the hardware to switch drivers (certainly not the largest obstacle but one to be overcome nonetheless), my lappy can do it with a switch and a reboot. I'm not sure how it works but you could look into how uniwill did it for ideas. Somehow they got windows to recognize what graphics card it is using and only boot with the drivers for that card; my guess is that there is some sort electrical connection that is switched back and fourth (if that is just vague enough) and the bios has something to tell the hard drive which driver to boot.

 

I get the feeling, like Gator notes, that the software end is the harder part. With enough modding (and time), you can get almost anything to run in whatever place you want.

 

Well, look at some of the Sony SZ's they have both the GMA 950 and 7400. But a reboot is required to switch between the different GPU's.

I would think if maybe that it would just work without any software?

I mean if I removed the on board graphics chip wouldn't it direct itself toward the external gpu? Like desktops, my old Compaq desktop had integrated graphics but I bought a 9600 for it, all I had to do was disable and uninstall the drivers for the integrated and install the 9600 and then install its drivers.