Originally Posted by Ice-Cold
now another question, what does ratio 1:1 mean? i'm currently using ratio: Full ... Can somebody explain
Intel CPUs use what's commonly called a Front Side Bus (aka FSB) to connect all of the major components such as the CPU, memory, chipset, and AGP socket.
On the most recent Pentium 4 models this FSB runs at a frequency of 200 MHz. However there are two things to keep in mind as this is where it can get confusing.
1) Intel Pentium 4 CPUs are quad pumped, meaning they can send 4 data "packets" (if I may call it so) per CPU clock cycle. Thus the effective frequency of Pentium 4 CPUs is normally 800 MHz (4 x FSB Freq. = 4 x 200 MHz).
2) Most recent RAM technology on the market is called DDR (Double Data Rate) and it can send 2 data "packets" per clock cycle. Let's take for example DDR RAM rated at 400: Its effective frequency is 400 MHz (2 x FSB Freq. = 2 x 200 MHz).
So if you have a Pentium 4 CPU with DDR 400 RAM they will both be running in synchronization at their original 200 MHz frequency.
Now let's say you start increasing your FSB to 220 MHz. What happens is your CPU is now running at 880 MHz (4 x 220 MHz) and your RAM is running at 440 MHz (2 x 220 MHz). Everything is great so far because both the CPU and RAM are running at the same frequency which is 220 MHz. Their speeds match and this is why the FSB:RAM ratio (or divider) is 1:1.
Suppose you continue increasing your FSB to 260 and your RAM cannot keep up with this frequency. It will lower its speed to say 208 MHz in comparison to that of the CPU which can easily sustain a frequency of 260 MHz. Now your CPU and RAM speeds do not match anymore. RAM is running slower than the CPU and the FSB:RAM ratio is 260/208 = 5/4.
Hope that helps