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GA-Z87X-UD4H: No USB Power?
In the process of building up a GA-Z87X-UD4H system, I notice that there
does not seem to be any power available on either the USB2 or USB3 outlets. I have not tried the internal USB3 headers pending purchase of a 3.5" front panel to use them. OTOH, on my EP45-UD3L, there is power on all the USB receptacles. Am I missing something? -- Pete Cresswell |
#2
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GA-Z87X-UD4H: No USB Power?
(PeteCresswell) wrote:
In the process of building up a GA-Z87X-UD4H system, I notice that there does not seem to be any power available on either the USB2 or USB3 outlets. I have not tried the internal USB3 headers pending purchase of a 3.5" front panel to use them. OTOH, on my EP45-UD3L, there is power on all the USB receptacles. Am I missing something? I don't know what to suggest. The advertising for your board says there is a fuse per port. http://www.gigabyte.com/products/pro...px?pid=4488#ov http://www.gigabyte.com/fileupload/p...8/8122_big.jpg The advertising shows a picture of a Polyfuse (the silhouette has the distinctive feature on one end of the device). Yet, looking at the motherboard picture, while I see a couple of what look like Polyfuses, they're pretty tiny. Usually, a Polyfuse is a bit bigger as components go. The Polyfuse is polycrystalline, it melts on overcurrent, it crystallizes when it cools off. That means the fuse recovers, and never needs replacement. It needs a certain size, for that chemistry to take place. So for so many amps of current, that dictates the X-Y size. While they could make the device thicker, I don't really see any taller SMT components in the region. So I can't say for sure, what current flow protection the thing is using exactly. There seem to be an awful lot of transistors in the area, but again, I can't be sure whether they go to those headers or elsewhere. It should have power, unless something is being switched off for some reason. Traditionally, at least for Southbridge ports, there is one OC# input for each USB port. That's "Overcurrent Active Low". When a logic zero appears on that signal, the Southbridge generates an interrupt stating that the measured current on the port is too high. But the method of current measurement is left to the motherboard designer. (On laptops, an 8 pin DIP per dual USB stack, measures the current and generates OC# flags. On a desktop, OC# is connected downstream of the Polyfuse, and when the Polyfuse opens, the OC# drops to zero volts along with the VBus level. Which is a cheap and clever trick.) Sorry I can't be of more inspiration. I can't really tell for sure what they're doing. Other weirdness includes, only one inrush capacitor per header. Implying the inrush is upstream of the dual fuses, instead of the more normal downstream position. Otherwise, their claim of a fuse per port would be a lie. If the inrush cap was downstream, we'd need to see two beefy caps per header. And I only see one. Intel recommends something like 100uF per port, and that holds up the VBus rail when a USB device is plugged in hot. Your board has some "iPad charger" settings, but as far as I know, what that does is set resistor biasing on D+ and D- of a USB port, so the iPad thinks it's connected to a legit charger. Something like that. I don't think that feature actually affects the power path. A charger port presents a different bias pattern, than a regular working USB port. The USB powering these days, is normally done from +5VSB. Your power supply has a 2 to 3 amp limit on +5VSB, so it's a relatively weak rail. Yet, your motherboard has ten USB3 ports (dual Intel, plus two quad port external chips?). If drawing 900mA from each port (the max), ten of those would draw 9 amps, or three times the power supply rating. I don't think this is an issue in your case, but it is a bit weird. While they could if they wanted, connect some of the USB3 ports to +5V (only powered when fans spin), that would then limit the "wake on" features, and also limit which ports could be used for "sleep charging". I assume in this case, when you say the ports aren't powered, this was with the system booted, and not a statement about iPod charging status when the computer is asleep. Paul |
#3
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GA-Z87X-UD4H: No USB Power?
(PeteCresswell) wrote:
In the process of building up a GA-Z87X-UD4H system, I notice that there does not seem to be any power available on either the USB2 or USB3 outlets. I have not tried the internal USB3 headers pending purchase of a 3.5" front panel to use them. OTOH, on my EP45-UD3L, there is power on all the USB receptacles. Am I missing something? Anything in BIOS ? I tried turning off usb 1.0, 2.0, 3.0 in my x58-UD3 however there is still 5v power since my cell phone charges from each port ok, but there is no signal for turning on the light in a pen drive. That was with the system on. Did not try with system off. When I got the board I installed the GA software to retain 5v usb power then the system is "off". |
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