It has the same description, and most of the features are the same, but just in case, because in the Xigmatek images it has a 6pin and 8pin PCIE connector, but on DinoPC, it only lists it as a single 6pin PCIE connector.
If you think that the Xigmatek VC ("Valued-Class") series NRP-VC503 is a 500 Watt power supply you have been thoroughly deceived by Xigmatek.
The NRP-VC503 is unable to deliver 500 Watts. It is more realistically a 350 Watt power supply because that is all it is capable of delivering.
The OEM is Solytech (a.k.a. Deer, Allied, Apex, L&C, Foxtech, Supercase) who caters to the el cheapo sector of the power supply market and is notorious for their exploding power supplies. If you don't value your system or its attached components then you get a unit made by this OEM.
Just stay away from the Xigmatek VC series. You've been warned.
Incase you didn't see.
It needs 2 PCIE connectors for the 550ti.
Also its pre-installed in the configuration.
I don't see a brand mentioned for the GeForce GTX 550 Ti card that you are considering.
The PNY VCGGTX550TXPB is the only GeForce GTX 550 Ti card, that I know of, where the manufacturer has specified that two 6-pin PCI Express supplementary power connectors are required.
A reference version GeForce GTX 550 Ti draws a maximum of 116 Watts (9.7 Amps) from the +12 Volt rail(s) under full GPU load so only one 6-pin PCI Express supplementary power connector is required on the card. In fact all of the other brands only have one 6-pin PCI Express supplementary power connector on their GeForce GTX 550 Ti cards.