What's the power port for?

[Synomenon]

So I've decided that the six USB ports on the back of my motherboard aren't enough and I don't want a hub taking up space anywhere.

I've been looking at these PCIe 1x USB cards:

http://www.newegg.com/Product/...6010%2cN82E16815283014


What's the point of the 4-pin molex power connector on the Bytecc card? The PCIe slot provides enough power for all the ports and the most a device can get from a port anyway is 500mA right?

Besides the power connector on the Bytecc card, the only other difference I see is that the Syba card has less capacitors. What's with all those messy caps on the Bytecc card?

 

[TC91]

i am not sure on how much power a pci-express 1x slot can provide, but i dont think it is not as much as a 8x or 16x slot. the syba has less capacitors maybe due to its capacitors having more capacity/of higher quality perhaps.

 

[Jiggz]

The Bytecc is the better of the two. The extra power connector is a must for high loads and to make sure you can connect more devices without overloading the PCIe slot. The Syba doesn't have the extra power so it's limited to 500mA (0.5 Amp) which is approx 6 watts at 12V. This is nothing considering an internal hdd typically uses 8-12 watts of power. This is the reason external hdd has external power.

 

[Aluvus]

Originally posted by: IsLNdbOi
What's the point of the 4-pin molex power connector on the Bytecc card? The PCIe slot provides enough power for all the ports and the most a device can get from a port anyway is 500mA right?

AFAIK the PCI-Express standard requires x1 slots to be able to deliver up to 3 A @ 3.3 V and 0.5 A @ 12 V. Card designers are much more likely to choose to regulate down the 12 V supply than use a boost converter to up the 3.3 V supply. So that gives you 0.5 A * 12 V = 6 W to play with. That would be enough to power 2 USB devices at their maximum power draw (2 * 0.5 A * 5 V = 5 W), if efficiency is high enough.

So no, that is not enough power for 5 devices.

Besides the power connector on the Bytecc card, the only other difference I see is that the Syba card has less capacitors. What's with all those messy caps on the Bytecc card?

The Bytecc card appears to have a bypass capacitor physically next to each port, which is good engineering practice. It may just have more components because it is based on an older platform, or because they wanted to be sure it really could handle high-drain devices.

 

[Synomenon]

Thanks for all the info. guys. Looks like I'm going with the Bytecc card.