These are Ethernet cables.
These are Ethernet cables.
The three cables on the right link to the power button, reset switch, and power LED. They link the motherboard to the case without connecting to the power supply. The middle cable with many colors plugs into a USB header (visible below the blue one, labeled "USB"). Your case includes two USB 2.0 ports or a USB port plus a card reader, so these connect to the header. These are unrelated to the PSU. The second picture shows a cable near the analog outputs, likely the AC97/HD audio cable, which connects the sound card to the case audio inputs (microphone and headphones). The header indicates "AFP," meaning "Audio Front Panel." To replace the power supply, simply remove the 24-pin connector, the 4-pin or 8-pin power connector for the CPU, and the power cables supplying hard drives, graphics cards, etc.