Dell released an article about the Thunderbolt 3 design in Dell systems. If you are experiencing issues including reduced data transfer rates instead of the maximum 40gbps or a single external display instead of dual video display, the reason might be the Thunderbolt 3 port on your computer is wired with only 2-lane PCIe. Therefore, you will be unable to use the maximum Thunderbolt 3 capabilities of 40gbps transfer or dual 4K 60Hz video.
http://www.dell.com/support/article/us/en/04/qna44089/thunderbolt-3-40gbps-data-transfer-rate?lang=en
Platform |
Lanes of PCIe capable via Thunderbolt 3 port |
Precision 3510 * |
4 lanes |
Precision 3520 * |
4 lanes |
Precision 5510 |
2 lanes |
Precision 5520 |
2 lanes |
Precision 7510 |
4 lanes |
Precision 7520 |
4 lanes |
Precision 7710 |
4 lanes |
Precision 7720 |
4 lanes |
XPS 12 2-n-1 |
2 lanes |
XPS 13 9365 2-n-1 |
4 lanes |
XPS 13 9350 |
2 lanes |
XPS 13 9360 |
2 lanes |
XPS 13 9370 |
4 lanes |
XPS 15 9550 |
2 lanes |
XPS 15 9560 |
2 lanes |
Latitude 7275 |
4 lanes |
Latitude 7285 |
4 lanes |
Latitude 5570 * |
4 lanes |
Latitude 7370 |
4 lanes |
Latitude 7280 |
4 lanes |
Latitude 7480 |
4 lanes |
Latitude 5480 |
4 lanes |
Latitude 5580 |
4 lanes |
Alienware 13 R2 |
2 lanes |
Alienware 15 R2 |
4 lanes |
Alienware 17 R3 |
4 lanes |
Alienware 13 R3 |
4 lanes |
Alienware 15 R3 |
4 lanes |
Alienware 17 R4 |
4 lanes |
Inspiron 7577 |
4 lanes |