elglanto

We've found that the NVidia Optimus features (pci-e x1 compression and internal LCD mode) would disengage if the NVidia driver detected an AMD GPU. To overcome that requires the dGPU to be disabled so doesn't appear on the pci-e bus using either the bios or using Setup 1.x. AFAIK the Latitude bios doesn't allow that so would need Setup 1.x to do it. That was under Windows 7. Windows 8 has a different driver model so I can't be sure if the same applies. Though I would speculate NVidia would still enforce that against it's competitor.

Latitudes also set a rather high TOLUD as described at http://forum.techinferno.com/diy-e-gpu-projects/2747-%5Bguide%5D-12-dell-e6230-gtx660@[email protected] making it difficult to host a eGPU in 32-bit PCI space. I was able to overcome that on the E6230 by having it boot and detect the eGPU after which the bios set a lower TOLUD. Is it the same on a E6540? In any case, disabling the dGPU using Setup 1.x will free up 32-bit resources to host the eGPU.

Only other issue may be with the HD8790M may use a special iGPU driver to obtain switchable functionality which may not be compatible with NVidia Optimus functionality. NVidia Optimus works great with the stock Intel iGPU driver. Of course if you would be using an AMD eGPU then that wouldn't apply since doesn't provide an internal LCD mode unless use third party LucidLogix Virtu software.

As we have no existing E6540 implementation you may be the first pioneer to work through sorting out how to do it.

I must admit that I don't like being the first trying those kind of things. But I am currently making a list of the laptop I am interested in for eGPU using the list you made to know the ones which are compatible. The latitude was just one of those but a very attractive one for me.

So if I understand correctly, if the laptop already has an internal GPU but an nvidia one like the Dell precision serie and the Lenovo W serie, it shouldn't be an issue right?

I could also check if the ATI GPU can be manually removed from the laptop but I doubt it.

Hello. I have a bit of a silly question but... I a very attracted by the Dell E6540 to do some eGPU but the one I am interested in already has a graphic card (AMD Radeon HD 8790M Graphics 2GB GDDR5). Is it an issue to do some eGPU? I don't see why but better ask before buying it!

Hello,

I plan to buy a thin laptop and do a eGPU for gaming with it but I am not on a rush. Thus, I would like to know if you think it makes sense to wait for more laptop offer with TB2 or not. I did some research and it seems that not a lot of laptops with TB2 are going to be released soon but I might be wrong.