Testing The Limits Of The Cooler Master EG200 eGPU Enclosure

Can Thunderbolt 3 Handle The RTX 3090?

Finding a GPU for sale close to it’s MSRP is the current equivalent of the quest for the holy grail, however there is a related product you can pick up on the chance you are one day successful in your hunt for a current generation GPU.  With the arrival of Thunderbolt external GPU enclosures have become practical for use with laptops and tiny systems, but with the hard limit of four PCIe 3.0 lanes of connectivity on Thunderbolt 3 just how much GPU can an external enclosure handle?

The Cooler Master EG200 is a 383 x 140 x 208mm box with three USB 3.2 Gen 1 Type-A out, a USB Micro-B 3.2 Gen 1 in and of course a Thunderbolt 3 compatible USB C port.  It also ships with a Cooler Master V Gold 550W SFX PSU to power whichever GPU is installed in the Cooler Master EG200.  Kitguru tested the enclosure with four different cards installed including an RTX 3060 Ti, RTX 3070, RTX 3080 and finally an RTX 3090.

Those who argue that the full power of 16 lanes of PCIe 4.0 are required by the mighty RTX 3090 will be somewhat miffed by the outcome of the testing.   In most cases that RTX 3090 proved 6-9% faster than an RTX 3080 when installed in the Cooler Master EG200, while you would expect about a 10-15% difference when using a desktop.  The performance of a card in an external enclosure is always slower than an internal card, but not by the margin implied by the bandwidth difference between PCIe 3.0 x4 versus PCIe 4.0 x16.

A final tip they offer is to use an external monitor, as the performance is significantly better there than when routed back into a laptop’s integral display.