Msi gtx 1050ti

My specs: Dell Optiplex 990 8gb ddr3 ram i5-2500 windows 10 500w psu I bought a MSI GTX 1050ti off of ebay and when I plugged it in and started it, I got a few beeps and nothing else. The fans and the leds on the card itself come on so it is definitely getting power from the 6-pin but no matter...

I really need a new CPU since my i5-4670k has a dying core and I'm torn between the 2700x and the 8700k and right now there is only £30 different between the CPU's on Scan UK. I'll mostly be using it for gaming (at 1080p 144Hz with a 1070 Ti, possibly upgrading to 1440p 144Hz at a later date)...