The processor speed is controlled by jumper bar -- actually a set of jumpers that are semi-intertwined. The wrong jumper bar or the wrong jumpers can set the clock speed too low. They are on the motherboard, when shipped, they are under a dire warning that your warranty will be void if you think about touching them. You would not want to touch them until you learn how to set them.
http://www.xlr8yourmac.com/G3-ZONE/yosemite/OC.html
Caution: running the processor without the heat sink in place is never recommended, but as these processor get faster, the heat Sink MUST be in place, or you can fry the chip. The clip that holds the heat sink is not symmetrical, and is intended to put maximum pressure directly over the processor die.
The individual jumpers are a smaller variety used in SCSI drives. They are 0.2 mm spacing, or 12.5/inch. The ones that you can get anywhere are 0.1 inch spacing, or 10/inch. Vendors often have no idea what they are selling, and designations like mini, micro and similar terms are often references only to jumper Height, not spacing.
