Two cables can both be USB-C and both say 240W, yet differ completely in whether they drive an external display or move files fast. This guide explains why power and bandwidth are separate specs, what the E-Marker does, and how to choose between 5Gbps, 10Gbps and 40Gbps.
A higher wattage doesn't mean faster transfer
Power delivery and data transfer are two unrelated specs.
MAGIC's three cables are the example. 5Gbps, 10Gbps and 40Gbps — all three have identical power specs, 240W (48V / 5A); the only difference is data speed. If you're buying a cable just to charge a laptop, the 5Gbps one is enough. The extra money buys transfer speed, not faster charging.
There are cables on the market that advertise high-speed transfer but only deliver 60W. When reading specs, check "power output" and "transfer speed" separately.
Not every USB-C cable can drive a display
It has to support DisplayPort Alternate Mode to push a display.
Of MAGIC's three cables, only the 40Gbps one (USB4 / USB 3.2 Gen 3) is rated for 8K/60fps video output and is compatible with Thunderbolt 3/4 devices. The 5Gbps and 10Gbps cables are data-plus-charging cables with no video output.
Video also needs both devices to support it. If your laptop's USB-C port doesn't support DP Alt Mode, no cable will give you a picture — check the laptop's specs before buying.
240W doesn't count without an E-Marker
Anything over 3A requires an E-Marker chip in the cable.
Without an E-Marker the charger only delivers up to 60W, and it won't show any error message. All three cables in MAGIC's USB-C 240W series have a built-in E-Marker and support PD 3.1 SPR (5V / 9V / 15V / 20V) and EPR (28V / 36V / 48V).
To reach 240W, the charger, the cable and the device all have to support PD 3.1 EPR. If any one of them doesn't, it falls back to a lower wattage.
So which one should I pick?
| Model | Transfer speed | Power | Video output | Best for |
|---|---|---|---|---|
| USB-C 5Gbps 240W | 5Gbps | 240W | None | Charging, the occasional small file |
| USB-C 10Gbps 240W | 10Gbps | 240W | None | External drives, backing up SSD footage |
| USB-C 40Gbps 240W | 40Gbps (USB4) | 240W | 8K/60Hz (DP Alt Mode) | Displays, Thunderbolt devices, fast SSDs |
The power column reads 240W on all three — that's the point made earlier: the expensive one buys speed, not charging. The transfer gap is concrete: the same 50GB project file takes a little over a minute at 10Gbps and more than twice that at 5Gbps.
If it's just for charging a phone at the bedside, the USB 3.2 Type-C 5A cable is enough.
Length and durability
High-frequency signals attenuate with length, and the faster the spec, the more sensitive it is — which is why 40Gbps-class cables usually top out at one or two metres. MAGIC's three come in 1.2M and 1.8M. If you need longer without losing speed, look for an active cable.
- Connectors rated for 10,000 insertions, in a one-piece aluminium alloy shell. Check this number if you plug your laptop in and out every day
- Thicker 30/24AWG tinned copper cores. Thicker conductors mean less voltage drop over distance and less heat
- Nylon braided jacket. Abrasion- and pull-resistant, so repeated coiling is less likely to break the cores inside
