An enterprising modder has made a discrete GPU using Thunderbolt for his Apple Macbook Air. The custom solution involves a lot of D.I.Y. and software hacks, but at the end of it all Larry Gadea achieved not only success to get the GPU working and communicating with the Macbook, but also some great gaming performance as well.
The solution starts with frustration, as many companies have been promising external graphics via Thunderbolt since its initial release by Intel in February 2011. Thunderbolt uses the same connector as Displayport but can additionally support other devices such as external hard drives, other computers, and as demonstrated here, faster external notebook graphics.
The external part is nothing new as it has been available to computer modders for a while. The PCI-Express bus on some laptops is open to devices using the Expresscard standard, and there are PCI-E adapters available that can be used to connect up a desktop graphics card for use in addition to the internal GPU.
Sony previously did this with the ultra-portable Vaio Z, offering an external AMD Radeon HD5670 graphics card on their “Light Peak” external GPU adapter. They were able to do this because Light Peak was the name that Thunderbolt was going to assume. Because it had no certification, Sony wasn’t able to sell the device separately.
Gadea’s solution uses a Thunderbolt-to-Expresscard adapter and he then jerry-rigs a Expresscard-to-PCI-Express adapter onto that along with an extra PCB that uses jumper settings to allow the external GPU to hijack the laptop’s monitor. It works at PCI-E 2.0 2x speeds which puts out 5.0Gb/s bandwidth rate and delivers surprisingly playable framerates in Borderlands 2.
The hardware work-around costs $250 and still requires an Nvidia graphics card, but some modders in the past have made their solutions incredibly thin using smaller power supplies and stripping graphics cards of unnecessary bulk.