Tower ECT1250, power for PCIe x1 USB 3.0 expansion card

@smidude​ , @TrevorMc ,

Correct.

You can split-it if needed, but there should be some spare SATA-Power-Cables hanging down by the lower 2.5in drive-bays.

Thanks guys. Out of town for a few days. Will follow-up at weekend.

Back into this. The only spare cable is a white square 4-pin labelled ATX CPU1; its twin is labelled ATX CPU2, connected to the ATX CPU1 motherboard socket. The 3.5" HDD I've added is connected by 2 leads - the 7-pin side to the blue 7-pin SATA3 HDD1 motherboard socket, the 15-pin side to the SATA PWR socket, also on the motherboard. Not sure where I go with this now.

STOP PRESS  just been informed by Dell Tech Support that <<....your Dell unit is equipped with a proprietary power supply that provides only the required connections for installed components. 

In this configuration, we see that there are no additional SATA or Molex power connectors available for auxiliary devices such as a USB PCIe expansion card.

As a result, the system does not offer a direct way to supply additional internal power from the PSU. >>

Had I known, I'd not have bought this device; left wondering why Dell would market it with 2 x PCIe x1 slots (in addition to the PCIe x16) if there was no facility for them to be powered.

Anyone have ideas on options? Or must I accept defeat and manage as best I can.....

@TrevorMc​ ,

The 3.5" HDD I've added is connected by 2 leads - the 7-pin side to the blue 7-pin SATA3 HDD1 motherboard socket, the 15-pin side to the SATA PWR socket, also on the motherboard. 

If this is a SATA-HDD, and is powered by a conventional (industry standard) SATA-Power Cable, then why not install a SATA-Power Y-Cable there, and tap your power from there?

Really appreciate all the help - good learning and probably more straightforward than looks. The HDD (second drive)  has 2 leads fed from 2 sources on the board - a 15 pin fed from a 7-pin at (blue) SATA0, and a 7-pin fed from SATA PWR - a black 6-pin rectangle. The PCIE needs 15-pin. I see on Amazon a 6-pin to 2x15-pins, so might be worth trying, although getting a bit expensive and time-consuming buying-in stuff which doesn't solve the issue and - against the grain - maybe best just settling for a USB hub.........

Thanks so much for your patience and help. The HDD's a standard Seagate 2TB. Pretty sure I've cracked it now - you've helped me 'think out of the box'. I'd been narrowly focussed on plugging into an unallocated feed on the board or coming out of the PSU - my previous HP Pavilion having a range of connections but nothing of the sort in this ECT1250, getting side-tracked with SATA pins and genders, completely overlooking the obvious of a simple male SATA Y lead feeding 2 x females, one for that side of the HDD, the other for the PCIe x1. Finding one of those leads in my 'bits box' it was a simple matter to put that together this morning and power-up, with immediate success.

Have to say I'm a bit surprised that Dell tech support didn't make that suggestion, but I'll feed it back to them hoping it might help someone else facing a similar issue. With hindsight, all a bit obvious really and disappointed it didn't occur to me before. But good learning despite time and a bit of cash spent. Thanks again & best wishes.