How to supply additional power to a USB3 card (with a molex connector) in a HP DL380G7 Server

I need to install a USB 3 PCIe card in a HP DL380G7 (ideally a 2 port card).
I saw that almost all the "low profile" cards use a "molex" connector to provide additional power to the one coming from the bus connector. The one I have is actually done in this way.
No molex connection is available inside the HP server (nor in other brands server we use like Intel's), so I wonder what is the best way to provide this extra needed power supply (the card without it does not work properly).
Are you aware if there is any USB card (low profile) that will work reliably without he additional power supply (need to have drivers for Windows 2008 R2) or any other idea about power connectors?
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office_equipment_centerDirector of TechnologyCommented:
Do you have any available sata power connections? You could use a sata to molex power adapter for the card.

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I am sure that your power supply has other connectors - USB requires +5v and 500mA per port; a molex connector provides +12v and +5v (+12v is yellow, +5v is red, ground is black).
Probably you have a floppy disk and is not in use any more so you can build a cable that will permit you to use the FDD power to feed the USB 3 PCIe
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beppe59Author Commented:
Thanks so far.

Here is an an external link that will point you to a similar discussion that documents why working with a HP server sometimes is not so easy.

Unfortunately I'm not expert at all about voltages, etc.
But I would like to try your suggestions (using the Optical Drive Sata connector) hoping that the USB3 board I have (a no brand) will be happy with the voltage supplied. Is there any risk of damaging the server?
If you short the wires or draw more current than they are rated for, you can damage the power supply.  It's usually not a good idea to add makeshift components to production servers, as their cost for replacement mandates taking extra care when changing configurations.  Have you considered the simple solution of a powered USB hub?
beppe59Author Commented:
Callandor thanks. But I suppose that to use at the highest possible speed an USB3 hub you need at least one USB3 port on the PC/server to connect it. This is the reason I want to install a card (the server natively offers USB2 ports).

I'm aware that a server usually is not a machine on which perform tests.... but I really need to access (write to) multiple external disks as fast as possible (the alternative is eSATA but I prefer to see if I can achieve the desired goal using USB3).
Otherwise I need to wait until someone will release a Thunderbolt interface card (with drivers for W2008......) hoping it will not have the same issue with required power supply.
Is the reason the card won't work without the molex connector because the card itself needs it, or the device it is connected to draws too much?  External hard drives need extra power, and powered USB hubs will provide it.  eSata is a good alternative, and hard drives cannot transfer data faster than the SATA interface (unless they are SSDs).
About eSATA, I've faced a similar problem with an eSATA PCIe card, it also needs extra power, without it the Server will aknowledge the card but not the drives.
The posibility I've been thinking about is to use the molex from the DVD or the FDD to power the eSATA card.
Here's a card that will work either way,  the extra power connector is optional and only if you need to deliver above USB 2 power levels.  Card has a SATA power connector as well,  so no need for a adapter if you have a sata power available.  If not one free you can get a sata power 'Y' adapter as well.

You can probably find the exact same card under a few different brand names.  Also the Startech card is only around $35 ish area through places like newegg,  not the $50 listed there.  

Fairly sure that you will find this is the case with most USB 3 cards.  The extra power port is required for any card to deliver the full 900 mA per port.  I don't know the numbers offhand but its probably more than the bus can deliver.

The amount of power is not going to affect the speed either.  This is just about the maximum power that can be delivered to a external device.  Using a external powered hub as was suggested is a good idea.  I believe external 3.5" drives still come with their own power supplies as well.
Buy a $20 USB powered hub.
beppe59Author Commented:
I finally used the internal the Micro-SATA connector for DVD with a cable adapter to Molex.
 I tried also the internal USB port (worked) but the other solution is more clean and leave the existing internal USB port free (we used it for a dongle).
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