Quote:
Originally Posted by yromenapri
Hi guys,
I'm planning on doing the express card eGPU with my next laptop. Only problem is, I haven't decided what my next laptop should be!
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See
Sandby Bridge notebooks for an eGPU.
14" Vostro 3450 a budget option with a quick HD6630M dGPU. 14" Lenovo Y470 with a GT550M a high performance option if your prepared to do a mPCIe eGPU - it's often on sale like quad core +BD for
$850. If can forgo the dGPU requirement then can go smaller and lighter like 12.5" Lenovo X220, 13/14" Toshiba R830/R840 or go a 900P LCD on a 14" Dell E5420 (eg:
$645 deal).
x1.Opt setup with Optimus dGPU Sandy Bridge notebooks?
wicked20 has confirmed that we can disable the Optimus dGPU so can run a x1.Opt eGPU instead. This is necessary as otherwise the eGPU runs at non-x1.Opt performance levels as if the standard desktop driver was installed. It seems the dGPU is given priority to Optimus functionality.
To disable the dGPU will require installing
Setup 1.x and booting via it; an updated release scheduled in the coming week. The disabling code ensures the NVidia dGPU does not appear on the PCI BUS at all so Win7 never sees it. This then liberates the dGPU's PCI space to now be used to host the eGPU. If installing Setup 1.x is too cumbersome for you (it's pretty easy actually) then consider HD3000 iGPU equipped notebooks only, though in the case of the T420 you'll encounter TOLUD issues with newer bios which the Optimus-equipped T420 will not experience.
See how this is done with a Dell XPS15 below.
Left: SB Dell XPS15 with Optimus GT540M dGPU active. NOTE: the XPS15 has no expresscard card slot.
Right: SB Dell XPS15 with dGPU disabled. Now has 512MB of contiguous PCI space from C0000000-DFFFFFFF, double what is required to host a eGPU.
x1.Opt setup with ATiAMD dGPU switchable gfx Sandy Bridge notebooks?
The code used to disable the NVidia dGPU did not disable a ATiAMD dGPU. It seems the ATiAMD driver is very persistent in finding cards that might be hidden on the PCI BUS.
To get x1.Opt working on those systems it would just require disabling the ATiAMD dGPU in Device Manager and/or using Setup 1.x to have the eGPU hijaak the dGPU's resources if there was insufficient space to host the dGPU+eGPU. This is done by performing 36-bit PCI compaction in Setup 1.x on the dGPU+eGPU, forcing the eGPU to 32-bit. Then the ATiAMD dGPU is moved into inaccessible 36-bit space causing Win7 to throw an error 12 against it.