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.
| 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 |