External graphics processors, or eGPUs, offer an extra boost for gaming on laptops and handhelds, but they come with some important limitations. An eGPU setup usually includes a desktop-grade graphics card placed inside a special enclosure, which connects to a compatible device through a Thunderbolt or USB4 port. This can help thinner or less powerful laptops handle more demanding games, but the performance gains are often not as strong as using a traditional desktop setup. One major issue is that using a GPU as an eGPU can lead to noticeable performance drops. Thunderbolt 4 ports offer up to 40Gbps of bandwidth, but only 32Gbps is typically used for PCIe data transfer, which is significantly less than the 16 lanes available in a standard desktop PCIe 4.0 x16 slot. Most of the GPU's workload stays on the card itself, with only some data needing to be sent over the cable. Testing from 2021 showed that using an RTX 2080 Ti in an eGPU setup led to performance losses ranging from 7 to 32 percent compared to a desktop. While these losses were smaller at 4K resolution, gaming on a laptop was still slower due to the cable handling both input and output. Recent tests by PC Gamer showed that even newer GPUs like the RTX 4070 Ti and 4090 experienced performance drops when used with Thunderbolt. In many 1440p tests, the RTX 4070 Ti ran about 25 percent slower over Thunderbolt than when connected via OCuLink, a direct PCIe connection. Upgrading to the RTX 4090 only gave modest improvements over Thunderbolt and OCuLink compared to desktop performance. The performance limitations of Thunderbolt become more pronounced with faster GPUs, making mid-range cards a better option for eGPU setups. Newer Thunderbolt 5 ports offer 80Gbps of bandwidth, and devices like Razer's Core X V2 use PCIe 4.0 x4, providing up to 64Gbps. This is still less than a full desktop setup, which uses 16 lanes. The Core X V2 enclosure requires additional components like a power supply and separate I/O docks, which can add to the overall cost. Despite this, the total cost of an eGPU setup with a graphics card is similar to a basic gaming desktop, which avoids the performance penalties of external connections. Thunderbolt 5 is currently limited to high-end laptops and workstations, while most Thunderbolt 4 laptops still use the older, slower 40Gbps connection. Alternative solutions like OCuLink use direct PCIe connections over cables, offering higher bandwidth but with less convenience. Apple removed support for eGPUs in 2020 with its shift to custom silicon, but recent software updates allow newer AMD and Nvidia GPUs to be used for AI tasks over Thunderbolt or USB4, although gaming is still not supported due to the lack of display output.