upgrading to W7 / USB3 Q's ? :-)

Hi all,

Have to soon upgrade Aunt's system box from XP Home edition to W7 Home
Premium,
....so before / whilst at it, I'll pop in a pcie x1 USB 3 card, and a Seagate
1TB Expansion Desktop Hard Drive,
....to pump up data transfer speeds whilst running (W7's) Files and Settings
Transfer Wizard, and later use for boot drive backups etc.

If I get a StarTech USB3 pcie x1 card with a SATA power connector on it, (or
a Dynamode brand that has a molex power connector on it),
....and get the above mentioned Seagate external hard-disk which is supplied
with a power supply,
....and NOT connect a SATA or MOLEX pwr supply to the x1 pcie USB3 card,
....will the external Seagate hd / USB3 lead try to suck out more current
that the pcie x1 USB3 card can supply, ....because I have not connected
extra pwr supply to SATA or MOlex connector on USB 3.0 card ?

best regards, ...and a Happy New Year to all,

Richard