USB Hub Generic Questions - Powered/Non-powered, Maximum Ports?

[mn8809]

Hello!

I just completed my second tower and I've run into a new dilemma. I went with an NZXT Phantom 530 enclosure and I'm absolutely thrilled with it so far. The only problem I'm having now is the lack of easily accessibly USB ports, I only have two in the front of the case.

I have a few questions that will help me decide if a USB hub is a viable option, or if I should suck it up and give my tower the old reacharound every time I need it.

1) Hubs I've used in the past never actually allow me full use of all the ports. For example a 4-port hub would only allow one or two actual ports to work. Is this because it was a cheap, unpowered hub?

2) Does the motherboard have an effect on how well a hub performs?

3) Can you give me a simple explanation of powered vs non-powered hubs? Is there any reason you would ever go with a non-powered?

4) I'm assuming the power draw of what is plugged into the hub may affect whether the other ports actually work or not.. Is this true?

5) In respect to USB 3.0 Hubs, is there any advantage in having 3.0 over 2.0 when you're plugging in a mouse/keyboard/headset?

I've done my fair share of googling, but I may be simply looking in the wrong places! If I've missed a great Tom's guide that covers all of this just link me and I'm happy to look into it myself.

I'm not sure if computer specs are applicable or not, but here they are just in case.

-Asus P8Z77 Mobo
-Raidmax Vampire 950+ PSU
-i5-2500k overclocked to 4.3GhZ
-Can supply anything else if needed!

Thanks guys!

 

[Saberus]

Let me see if I can shed some light on this, though I've probably been ninja'd.

1) Likely yes, unpowered hubs have to share the power from the host port, which is usually 500mA for 2.0 and 900 mA for 3.0, and even unpowered hubs will take some of that power to run their internal signalling.

2) Yes and no. If the host port on the motherboard is a high-power port, it can mean more power available to the hub's ports. It could also be moot if the unpowered hub has power regulation and basically blocks any excess power beyond the 500 mA spec.

3) Unpowered hubs borrow some of the power from the port to run their internal switching and signalling, and divide the rest to any used ports as the device connected demands. Powered hub have an external power supply to feed a full 500/900 mA to each port. Powered is the way to go if you're hooking up hard drives.

4) See above, but yes, if there's not enough power for a device, it will not run, and it will look like the port is non-functional.

5)No, keyboards and mice are actually USB 1.1 devices and don't support higher bandwidth, with the exception of keyboards that have hubs built into them. Some are just for the mouse and other low speed devices, and some are full 2.0 or 3.0 for thumbdrives. Plugging a device into a faster port than it was designed for will not make it faster.

 

[mn8809]

Very informative, sounds like a powered hub is all I really need.

Thank you!

 

[tazextremedevil]

TY!

 

[Paperdoc]

I fully agree with Saberus with minor exceptions on items 4 and 5. I'll also provide some guidance in choosing a Hub.

4. Power used by other devices on the Hub does limit what power is available to a new device on UNpowered hubs. With a Hub that has its own power supply, all Hub ports SHOULD have the specified capability (0.5 amps per port for USB2, 0.9 amps for USB3) irrespective of what the other ports are doing. (I say SHOULD, and see below for why.) However, I'll note a factor that is especially applicable to "portable" and external HDD units on a USB3 hub. Current designs of the "Portable Hard Drives" sold for use with laptops and USB3 ports do work just fine. They are designed to work within the 0.9 amp limit on power supplied by the port. But there are two cases where problems can surface. One is when you try to use such a drive on an older USB2 port (or, use a USB2 cable that lacks all the correct wiring). Then typically what happens is that the drive does NOT appear to do nothing at first. It actually appears to be working. But as soon as you try to read or write it fails because there is not enough power to spin the disks and move the heads. The second is cases where you are trying to use a drive NOT designed for low power consumption on a laptop USB3 port. This can happen, for example, when you mount a desktop HDD inside an enclosure that uses a USB data connection, and fail to provide adequate power to this unit from the separate power supply module that came with the enclosure. This case certainly may produce obvious total failure to function.

5. It's quite true that such devices cannot use the higher data transfer rates of a USB3 system. However, there still is an advantage to using a powered USB3 Hub with them - they still contribute to power consumption at the Hub.

Now for buying purposes, what to look for. First, as you're probably aware, stay away from things called "Bus-Powered Hub". All that means is that all the power for the Hub and its devices is drawn from the host's port - in other words, these are really UNpowered Hubs. Get only a Hub that comes with its own power supply "brick".

Next, what is "adequate" power? Some Hubs are sold with their own power "brick" that in not really adequate. Start with the requirement: a USB3 port must supply 0.9 amps at 5 VDC to EACH of its ports, and all of the ports should have that available simultaneously. Some Hubs even have special "non-standard" USB3 ports they call "charging ports" that can supply more, but for now we'll ignore that additional power. The tricky part is that many Hubs come with power "bricks" that supply at 12 VDC, and the Hub changes that to 5 VDC. So, the thing to focus on is WATTS per port, not Amps. 5 VDC at 0.9 amps is 4.5 WATTS PER PORT. So a USB3 hub with 4 ports will require a supply from its "brick" of at least 18 W, plus a little for its own internal use. Round that up to 20W, no matter what the "brick's" output voltage is. At 12 VDC, for example, the "brick" needs to be able to supply the Hub with at least 1.7 amps. So look for a system that includes a power "brick" able to provide to the Hub at least 5W PER PORT or, if it's a 12 VDC output, 0.42 Amps PER PORT. IF the Hub claims to have a high-power Charging Port included, make sure its "brick" can supply the additional power for that.

Of course, if you are sure that your will use a multi-port USB3 hub but never need the full power on all ports simultaneously, you might be able to work with one that has less power supplied from its "brick".