Hey guys going to be building my pc tomorrow actually won't have my 1080ti yet but that's all I'm missing do I need a capture card or will the software that comes with the 1080ti work good?
With modern GPUs from AMD and Nvidia both supporting some form of hardware-based video capture, basic video capture should work fine as long as your streaming software supports Nvidia's shadowplay or whatever AMD's equivalent is called.
A capture card is mainly necessary when you want to use a separate PC for recording/streaming to eliminate any chance that streaming may interfere with the main PC's performance or when the main PC simply doesn't support a satisfactory form of local recording, such as recording BIOS or OS installs where there is no working OS on the computer to record from.
With modern GPUs from AMD and Nvidia both supporting some form of hardware-based video capture, basic video capture should work fine as long as your streaming software supports Nvidia's shadowplay or whatever AMD's equivalent is called.
A capture card is mainly necessary when you want to use a separate PC for recording/streaming to eliminate any chance that streaming may interfere with the main PC's performance or when the main PC simply doesn't support a satisfactory form of local recording, such as recording BIOS or OS installs where there is no working OS on the computer to record from.
OBS can use AMD's and Nvidia's hardware to encode, no load on the CPU. NVENC and AMD uses h264 hardware encoder (at least on my AMD card, could be h265 on newer cards). So no, capture card is not needed.