How to upgrade a free optiplex into a fire hazard / gaming beast

Hello, I've just recently acquired and optiplex 5050 SFF and a gtx 1660 super for free. I have the PC up and running perfectly but im not sure if I can connect the GPU to it since the GPU need an 8 pin connector on the front of it, I'm not concerned about anything fitting in the case properly, I just want to know if I can connect it, or what I would need to buy to get this free pc gaming ready (elden ring?). The psu says "Maximum continuous total DC output power shall not exceed 180W". If the psu is too little can I underclock the gpu to use it, perhaps data to 8 pin connector or something like that? Service tag: HLN8D92