i have 2 cisco catalyst 3750G's, and a stack cable a have a question about the stack does is transfer power so do i only need 1 power cable or 2 and is there a way to reset the password without a serial cable
Stack cables only transfer data, not power. Both switches need their own power cable. Newer models (e.g. Cisco 3750-X) do support Cisco's StackPower cables. You can then create a setup where one switch has two power supplies and the second switch have none. In those models you will have two sets of stack cables: (1) normal data stack cables, and (2) stackpower cables.
Unfortunately, what you are trying to achieve is not possible. On the older 3750(G) models there is no power stack feature available, as Tommiie has written. Also you cannot reset the password without a serial cable.
There is however a possibility to get redundancy on older model switches and routers:
You can use the Cisco Redundant Power System 2300 on older models like the Cisco 3750, 3560, 3550, 2960-S, 2960, 2950 series etc.
There are two types of RPS cables:
- CAB-RPS-2300-E= (22-pin-to-22-pin cable for use with Catalyst 3750-E and 3560-E switches)
- CAB-RPS-2300= (14-pin-to-22-pin RPS cable for use with other supported network devices)
The Cisco RPS 2300 is a redundant power system that provides users with uninterrupted network services in the event of an internal power supply failure. The Cisco RPS 2300 is used with fixed-configuration Cisco Catalyst switches, including the Cisco Catalyst 3750 switches, and routers such as the Cisco Integrated Services Routers. The Cisco RPS 2300 helps ensure failover from internal power supply failures for one or two of up to six connected switches or routers. It automatically senses when a connected device has experienced an internal power supply failure and immediately begins to supply power to the device, providing continuous uptime with no device reboot.
The Cisco RPS 2300 system supports Power over Ethernet (PoE) as well as data-only service. However, the total power available to the switches depends on the number and capacity of power supply modules in the Cisco RPS 2300.
For instance (and sorry i couldn't find a better table):