|Expanding on Finger's comments....|
The GT 610 is a low end card & doesn't require additional power. It's a rebranded GT 520 & isn't much better than the i3's integrated graphics. The major benefit is that it has dedicated memory. Make sure it's fully seated in its slot & the monitor cable is connected to the card. It should work immediately, at least to be able to enter the BIOS & tweak the settings. The integrated graphics should be disabled & the PCIe slot set as the primary display.
Do you hear any beeps when the card is in place?
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