Thats the connector for the front USB ports and not the power cable.
It's a Lenovo cabinet, right? What's the model number
Where is the power supply unit?
+1 for that.Bhaiyaji aap kisi computer shop pe krwalo isse sahi woh krdega
Not the power cable. More like the power button cable.
So what I am guessing is, you have bought a new motherboard + processor and you are using an old cabinet. The power button header is a weird one for your cabinet and does not fit on your new motherboard. Your old PC was a branded one? If yes, then this is something which OEMs do to lock their customers from upgrading.
What I can suggest you is, buy somekind of Jumper wire cables. Like these - Breadborad jumper wire 28pcs Pack - Female to Female | Simple Labs get rid of one female part. Cut the cable coming from power button and make manual wire connections. The female part goes onto the jumper. What else can you do? Aside from buying a new cabinet.
Avoid using native languages while posting outside Chit-Chat section. Many people don't know it and many like me feel dyslexic when Hindi is written in Roman script instead of Devanagari. If you really want to do it, do it properly. And people having only "lol Facepalm" as their contribution to this thread should take notice that if I see that smiley unnecessarily being used you, you might get ban. Beter spend some time to understand the problem.