let's say you have this as a extreme gaming PC(this will be an example ok and i doubt most of them would work together anyway)
I7 3960X (Processor) Overclocked to 120.50Ghz (LoL)
asus rog x79 rampage (Mobo)
128MB team elite ram (RAM) single
Nvidia Geforce FX 5100 128MB Video Memory (GPU)
Mini ITX(any case well this part seem stupid but i'll just put it for the LOL)
550" Samsung HDTV 19200X12000 Resolution (LOL TV)
Razer Illusion gaming mouse (10 DPI)
Thermaltake Whip keyboard ( 20 key's keyboard)(10 hours life time)
Noctua NH-D10,000 (50"long, 50" wide) CPU Cooler
Plastic Chair with Leg on the right side(Lol)
just looking at the parts above you can already see a lot of bottleneck (things that doesn't work well together or in other words, it will be component which is making you lose performance)
let's say you are playing a basketball game 5v5 in your team you got 3 crippled player, 1 uses a wheel chair, and 2 uses those wood stick, and your like a 100000 star basketball world class player so then in that game on your team the bottleneck would be those 3 mice.
i5 2500K
msi z68a-gd80 G3
Nvidia Geforce FX5100 (this is the bottleneck)
2TB WDCB 7200rpm 64Mb Cache HDD
128gb crucial m4 ssd
on this system the bottleneck which is pulling the system down the level of the performance it should perform but since it's being pulled down, instead of performing A+ it's going down to D-