[SOLVED] Just bought a PCIe -> USB card, what is the extra power cord for?

[KarlJay]

Just got a Vantec USB 3.0 4 port PCI express card (UGT-PC341)

It comes with a power cable and I have no clue why.

So I'm building a dual boot macOS High Sierra or Mojave / Win7. I got this card because my 2 month old High Sierra was losing keyboard and the mouse was acting funny. So it looks like my USB wasn't working wright so I bought this card.

No idea what amperage it is, doesn't seem to have mac specific drivers, but others are telling me it's about the more modern chip or driver or something, so I'll try it.

It has an 8" power cord that ends the same as the old classic 4 pin PC power end.

I assumed it would get power from the board, but have no clue what difference it make if I use this cord (IF I can figure out where to plug it in).

Anyone ever use one of these and can offer any insight?

 

[Shektron]

I checked out the card, and I'm not sure about this, but I think the power cord is to supply power to some other component from the extension card, using the cable. I can't say this for sure, but I'm pretty sure that's what it's for, because the card couldn't possibly use so much power that just the PCI-E slot isn't enough.

 

[CountMike]

I checked out the card, and I'm not sure about this, but I think the power cord is to supply power to some other component from the extension card, using the cable. I can't say this for sure, but I'm pretty sure that's what it's for, because the card couldn't possibly use so much power that just the PCI-E slot isn't enough.

You are right, it's there to ad some more power to USB ports on that card. Most of them have it. It's a PCIe x1 card and full 75W are available only for PCIe x16 slots. If all 4 USB ports were used at full power, PCIe x1 could not supply it.
Need to connect to a Molex plug coming from PSU.

 

[Shektron]

You are right, it's there to ad some more power to USB ports on that card. Most of them have it. It's a PCIe x1 card and full 75W are available only for PCIe x16 slots. If all 4 USB ports were used at full power, PCIe x1 could not supply it.
Need to connect to a Molex plug coming from PSU.

Actually, that's not what I meant, but let's not confuse anyone by stating what I meant. I hope OP's question has been answered.

 

[Paperdoc]

CountMike is correct. The root of the issue is that the PCIe bus was never designed to provide a lot of power to cards plugged into it, but it does use fast data transfers. So a card to provide USB3 ports makes good use of the data transfer ability, BUT the USB3 standard also requires providing power at 5 VDC and max 0.9 A PER PORT to any USB3 device plugged into it. So the CARD does not use a lot of power, but its attached USB3 devices do. The card comes with a cord that plugs into a 4-pin male Molex connector on the back of the card. The other end of that cable plugs into a female 4-pin Molex output from the PSU, often called "Peripheral" on a PSU. Just in case you don't have one easily available, it also comes with a small adapter to allow this cable to connect instead to a SATA power output from the PSU. Unfortunately, the manual for that card does not tell you about this, except to say in the section on Troubleshooting that, if you get a warning message about insufficient power, you should check to be sure all the power sources are connected.