As a matter of fact, chips (CPU,GPU,and RAM) are now so fast that the MOST limiting factor in modern systems is the trace pathways and connectors on the motherboards. Old traces used to be cheap tin-copper mixes that were pretty wide (about 1/32nd of an inch). But since most chips speed (back then) was measured in KHz, along with the low number of total chips and connections, it worked fine. However, modern systems now use 4-5 times the amount of chips with 4 times the amount of connections between them. Even using multi-layer PCBs with micro-trace pathways using silver-doped lines (of around .4 hundredths of an inch), they simply don't have the capacity or transmission clarity (impedance-related cross-talk and quantum-tunneling effects) to 'speed up' much more without risking data errors and signal degradation.
Manufacturers have spent the last 5-7 years looking for new transmission technology to break through this. IBM in particular, has been researching into 'optical boards' that would use fiber optic transmission between chips that would allow speeds 100 times faster than what is presently available now, using less energy and with greater signal distance and fidelity. The trick has been creating 'mini-lasers' on chips to send signals, and the receptors to read them. IBM announced that they have come up with a solution that they are currently testing, and hope to have available for wide-spread commercial use in 2-3 years.
