# USB 3.0 - Not enough power?



## Sweetchuck (Sep 10, 2008)

I have a Dell Studio XPS 7100 desktop (AMD Phenom II X6 1055T, 6GB RAM, 1GB ATI Radeon HD 5870, 460w PSU, don't know what mobo) and am having problems adding USB 3.0 ports to my machine.

I recently bought an Icy Box IB-273StU3 USB 3.0 enclosure for a 2.5" portable HDD, and also just installed a TeckNet USB 3.0 PCI Express Interface card (2 x USB 3.0 ports). I plugged the card into the spare PCI slot on my mobo, booted up and installed the drivers. Everything went swimmingly until I plugged in the HDD. First, the PC didn't recognise it. A few tries later and it finally recognised the drive, but when I tried to copy anything from it, the PC lost the connection to the HDD (showed up as having been unplugged even though it was not).

The card was advertised as not needing an additional power supply, but to my mind this sounds exactly like the drive isn't getting enough power. I checked the card and saw that it has a molex connector (which suggests that it probably does need a power supply). Unfortunately, the only spare power supply cable from my PSU is a SATA-type connector for the (unused) spare optical drive bay. I plugged in a SATA-to-molex connector and then hooked this up to the PCI card and tried booting up again, but still the same problem: my PC only intermittently recognises the drive, and drops the connection altogether when I try to copy anything to/from the portable HDD.

I'm trying to find somebody else with a USB 3.0 port so I can test out the Icy Box on a confirmed working port, but nobody I know has invested in USB 3.0 yet.

Does anyone have any idea why this is happening? I have tried using different USB 3.0 cables and the same problem occurs. The Icy Box works fine over USB 2.0. It has no dedicated power supply socket, so would my best bet be to invest in a USB 3.0 Y-Cable which will also plug into a spare USB 2.0 socket for extra power? Or does it sound like my PSU is simply not powerful enough for my system?


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## epshatto (Dec 23, 2010)

> AMD Phenom II X6 1055T, 6GB RAM, 1GB ATI Radeon HD 5870, *460w PSU*


I'm really surprised this is working at all. I don't know what make & model PSU you have, but I would think 460W is waaaay underpowered for your rig. I would consider 800W or higher, of a good quality PSU.

I'm not 100% sure your problem is power-related, but you really do need a better PSU than that. If you have any other devices you can plug into the PCIe card, I would try that to rule out a faulty card.


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## shawnpb (May 30, 2010)

I agree 460w is way too under power for your rig with all that you have in it graphics card with 1GB RAM and 800Mhz clock speed GPU. As mentioned you need at least a 800w PSU.


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## westom (Aug 28, 2009)

epshatto said:


> I'm not 100% sure your problem is power-related, but you really do need a better PSU than that.


 Most computer techs have no idea how electricity works. So we estimate what the all computers need. Then tell computer techs to double that power.

Anyone can tell in less than a minute if the a PSU is undersized or defective by using a multimeter.

Brand name computers use what hearsay calls too small because most all computers consume between 200 and 350 watts. Or is your computer outputting heat like a four slice toaster? No computer really needs an 800 watt PSU.

Numbers posted from a multimeter can eliminate any power question immediately. If a USB port could not provide sufficient power, then excessive power demand triggers a power surge message and cuts off the port. If the drive can be powered by a USB 2.0, then the 3.0 port has more than enough power. Nothing posted even implies a power problem. Is a classic symptom of signaling problems; not power problems.

USB 3.0 ports are a USB 2.0 port with separate 3.0 hardware added. If suspects are ordered according to speculation, most suspect bad USB 3.0 signal hardware on the computer, cable, or disk side. USB 2.0, USB power, and undersized PSU are far down on a suspect list.


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## Sweetchuck (Sep 10, 2008)

Thanks for the advice, guys.

Am I not right in thinking that Dell uses under-powered versions of popular GFX cards in order to include lower-wattage PSUs in its systems?

Even taking that into account, presumably you still think I should be looking at a better PSU. How much (ball-park figure) do you think a decent 800w PSU would set me back? I've had a quick look on Amazon but there is a wide range and I don't know exactly what I should be looking for. I don't need a modular one; just a reasonably priced and reliable PSU with no real bells and whistles...


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## Amd_Man (Jan 27, 2009)

Todays Pci-e based graphic cards, quad cores and USB inputs use alot more power than previous generations. A 350w power supply may have been fine 10 years ago, but not today. I've seen reviews on high end graphics cards and just the card alone draws 300+ watts under full load and I know exactly how a power supply works.


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## Sweetchuck (Sep 10, 2008)

Would the GFX card be drawing that much power even if I'm just working in Windows Explorer? My 2.5" USB 3.0 HDD is crapping out even when there's no real GFX load being processed.


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## Amd_Man (Jan 27, 2009)

I'm not saying your GFX card draws 300+ watts but the min recommended for your card is 500 watts. A quality 750w would give you more than enough power. More is alot better than not enough when dealing with computers.


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## Tyree (May 10, 2009)

I doubt the underpowered PSU relates directly to your problem but the Minimum suggested power for a 5870 GPU would be 650W with a good quality PSU.
You need to determine that the PCI-3.0 card and the Hdd enclosure are working properly.
My first suspicion would be the add-in card. Try using the external Hdd in a USB port on the Mobo to determine if it will work properly.


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## westom (Aug 28, 2009)

Sweetchuck said:


> Even taking that into account, presumably you still think I should be looking at a better PSU. How much (ball-park figure) do you think a decent 800w PSU would set me back?


 First, power supplies must not be selected by watts. Critical selection numbers are amps for each voltage. How many accuse your supply of being underpowered but don’t cite the important numbers – amps? We tell them they need double those amps by talking in vague terms – watts. The majority informed by salesmen recommendations will cite 800 watts because that is popular hearsay. Then nobody need learn how electricity works.

Dell put the right supply in because engineers (not computer assemblers) designed the system. 

But again, how many computers are so hot as to also toast bread. If you need 800 watts, then a computer alone will heat a room. Heat measured by a hand says many only know what engineers encourage. So that they spend more money on supplies and don't waste customer service time. 

Now, if your power is a problem, then the supply is defective; not undersized. How to know immediately? Buy or borrow a multimeter. Three digit numbers from four wires will provide so many facts that it may become the longest post here. Those four numbers contain that much information. Meanwhile, deal with far more likely suspects.

If a USB port is starved for power, then the computer was crashing repeatedly before the USB port was installed. Tiny power demanded by a USB port would not cause only a USB port to fail. Your USB symptoms are classic of another and separate USB function - signaling. Deal with what the symptoms suggest. Not accusations that engineers in Dell are too dumb to install a sufficient supply.


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## Sweetchuck (Sep 10, 2008)

Tyree said:


> I doubt the underpowered PSU relates directly to your problem but the Minimum suggested power for a 5870 GPU would be 650W with a good quality PSU.
> You need to determine that the PCI-3.0 card and the Hdd enclosure are working properly.
> My first suspicion would be the add-in card. Try using the external Hdd in a USB port on the Mobo to determine if it will work properly.


The external HDD works absolutely fine via USB 2.0 and in other enclosures. I don't have any other USB 3.0 ports to try this in (or know anybody who has one I could use), other than the ones I am trying to install.

I'm not sure how else I can go about testing the PCI card.


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## Tyree (May 10, 2009)

To me, that indicates a problem with the add-on card or the drivers.


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## westom (Aug 28, 2009)

Sweetchuck said:


> I'm not sure how else I can go about testing the PCI card.


 You cannot. Testing requires equipment that costs $thousands. You have three unknowns. Signaling defects from the PCI card. Signaling defects created by the cable (counterfeit cables can be a problem on a standard this new). And signaling in the disk drive box.

Again, because you seem to be ignoring what is the actual problem. USB 3.0 is two separate USB ports in one assembly. USB 2 and USB 3 hardware are electrically separate and wrapped in a common container. Your USB 2 signaling hardware (at both ends) acts as if fine. Something may be wrong with your USB 3 signaling hardware. Which of three suspects? Your only alternative is to shotgun. And ignore popular and irrelevant myths about undersized power supplies. Your symptoms (ie USB 2.0 works) says power is sufficient.


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## Amd_Man (Jan 27, 2009)

westom said:


> Dell put the right supply in because engineers (not computer assemblers) designed the system. QUOTE]
> 
> Dell uses low quality power supplies, always has and always will. Their power supplies are just enough to run what they came with. You start adding hardware especially a graphics card then the unit no longer has the required power to safely run the system.


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## Tyree (May 10, 2009)

The fact the the OP has a low quality underpowered PSU has been established so lets stay with the USB issue.
The external device works with the Mobo USB port.


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## westom (Aug 28, 2009)

Amd_Man said:


> Dell uses low quality power supplies, always has and always will.


 Which is hearsay from computer assemblers who have no electrical knowledge. How many computers did you design? How many power supplies? If the supply is undersized, then you have used multimeter numbers to identify each one. We who did this stuff tell computer assemblers to buy supplies that are twice too large. Then they will not waste our time with problems directly traceable to insufficient technical knowledge.

An undersize supply does not explain the OP’s problem. Not for a minute. It is a Dell. Power does not explain any of the OP's symptoms. Please address the OP's problems. Not distract him with irrelevant and popular urban myths.

It works on USB 2.0. Therefore power is more than sufficient. Most do not even know USB 2 and USB 3 functions are electrically separate. Again, basic electrical knowledge. His USB 2.0 signaling works fine on that power. His USB 3.0 signaling does not work on the same and sufficient power.

Symptoms imply a problem in the USB 3 signaling system. Not power. 

If his supply was undersized, then the computer was crashing long before he installed a USB card. If a supply was undersized, then his computer was crashing; not a disk drive intermittently disconnecting. Deal with the USB problem; not some wild speculation about power that does not explain any of his symptoms.


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## Tyree (May 10, 2009)

@ westom
Read my Post #15.


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## Sweetchuck (Sep 10, 2008)

westom said:


> Which is hearsay from computer assemblers who have no electrical knowledge. How many computers did you design? How many power supplies? If the supply is undersized, then you have used multimeter numbers to identify each one. We who did this stuff tell computer assemblers to buy supplies that are twice too large. Then they will not waste our time with problems directly traceable to insufficient technical knowledge.
> 
> An undersize supply does not explain the OP’s problem. Not for a minute. It is a Dell. Power does not explain any of the OP's symptoms. Please address the OP's problems. Not distract him with irrelevant and popular urban myths.
> 
> ...


Would an external HDD connected by USB 2.0 draw just as much power as it would when connected by USB 3.0? I thought (perhaps naively) that USB 3.0 would be a bigger power draw.


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## westom (Aug 28, 2009)

Sweetchuck said:


> Would an external HDD connected by USB 2.0 draw just as much power as it would when connected by USB 3.0?


As posted previously. If a USB device demands too much power, then the USB announces a power surge and cuts off power. USB ports provide near zero (trivial) power. Exceed that number and the USB port declares a power surge.

Your symptoms are classic of a signaling problem. Listed was a suspect list. Unfortunately equipment necessary to identify which is defective requires too much money and knowledge that does not exist here. Your only solution is to shotgun those suspects. Keep replacing / swapping parts until something works. Power is only blamed when other more relevant knowledge is unknown.

Your symptoms say the USB 1, USB 2, and power functions are working fine. Your symptoms suggest a problem only with the USB 3 (signaling) function.


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## Sweetchuck (Sep 10, 2008)

Hi guys. Apologies for the silence but I've been waiting for a USB 3.0 flash drive to arrive. It came this morning, and I have tested it in the same USB ports, and I got some interesting results.

It doesn't seem to be a USB 3.0 signalling problem, because the drive works fine in both of my new USB 3.0 ports. It transfers fine, although not particularly quickly. This, however, is due to the limitations of the flash drive and not my ports (the flash drive is a Transcend Jetflash 700, which tops out at just 20MBps, despite being USB 3.0).

However, something else happens when I plug either the external HDD or flash drive to my USB 3.0 ports. Basically, some of the USB 2.0 ports on my PC (the ones closest to the USB 3.0 ports on the rear of my case) stop working. I have a Logitech wireless keyboard which simply stops responding when I plug in the USB 3.0 peripherals. If I remove the keyboard dongle and plug it into the USB 2.0 ports on the front of my PC, it works fine even with one of the USB 3.0 peripherals plugged into one of the rear USB 3.0 ports. However, I also have another USB 2.0 peripheral plugged into the rear of my PC - a Logitech speaker system which has an external AC PSU. This carries on working from the rear USB 2.0 ports even with something plugged into the USB 3.0 ports.

Surely this would indicate conclusively that a lack of power is exactly what's wrong with my PC after all?

Thanks again for all your help.


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## epshatto (Dec 23, 2010)

PSU. Get a new one, and a better one, and ignore the engineer.


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## Tyree (May 10, 2009)

Your PSU is ceretainly low quality and underpowered so replacing it is a win/win situation but I have my doubts about the PSU being the problem. Your testing, to me, suggests a Mobo problem.


Sweetchuck said:


> The external HDD works absolutely fine via USB 2.0 and in other enclosures.


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## Sweetchuck (Sep 10, 2008)

Tyree said:


> Your PSU is ceretainly low quality and underpowered so replacing it is a win/win situation but I have my doubts about the PSU being the problem. Your testing, to me, suggests a Mobo problem.


What is it about this that suggests a mobo problem, and what kind of problem?

If there was a mobo problem, surely neither flash drive nor external hard drive would work in the USB 3.0 ports? As it is, the flash drive works fine, whereas the external HDD does not. Given the additional power required to spin the platters, surely this is just a very simple power shortage in my system?


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## westom (Aug 28, 2009)

Sweetchuck said:


> Given the additional power required to spin the platters, surely this is just a very simple power shortage in my system?


 Many hundreds of watts that power everything else is suddenly too few when a USB disk drive demands a massive 5 watts? And that 5 watt load does not cause anything else to fail? Please. That 5 watts is near zero power. Any recommendation that ignores these numbers is best called wild speculation.

Your USB contains separate hardware functions. Apparently its USB 1 , USB 2, and power functions are working just fine. USB 3 hardware is apparently defective. Each function is distinct and separate hardware. So, is the USB 3 defect in that disk drive interface, cable, or USB port?

You have zero reasons to suspect power. If power is insufficient for USB 3, then power is also insufficient for USB 1 and USB 2. Causing a power surge error message. And causing many other computer components to also fail. You are not seeing that because power is more than sufficient.

How does a 5 watt load affect a supply that is outputting hundreds of watts, without failure, to everything else? Simple. Mythical failure. Buy silver crosses to drive out the evil demons. Or deal with what is a reasonable suspect.


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## Tyree (May 10, 2009)

To clarify westom's post, your power is sufficient for USB but not for your PC as a unit.
You need to be at 650W minimum, with a good quality PSU, for the 5870 GPU.


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