X-bit labs

CPU Overclocking Guide (page 3)

Category: CPU

by Doors4ever

[ 10/04/2005 | 10:46 PM ]

Accessing BIOS Setup

How do we get there? Usually all you have to do is press the <Delete> key on the keyboard during system boot-up. You can do it multiple times, just to make sure. Don’t disregard the information that appears on the screen. Read it. Sometimes, it may also be useful to look through the mainboard manual before getting started, because sometimes there might be a different key or combination of keys assigned to let you into the BIOS Setup. Gigabyte mainboards, for instance, require the user to press <Ctrl+F1> once you get into the BIOS, otherwise, you will not be able to access any of the options there. As a result, you should see the following screen:

Don’t be confused by a lot of unknown words and terms. Even though the BIOS versions are different and some options may be called differently, we will still find everything we need just fine.

For our overclocking experiment we need to increase the CPU frequency, which is calculated as the CPU clock frequency multiplier multiplied by the bus frequency. For example, if the nominal frequency of the Intel Celeron D 310 processor is 2.13GHz, its multiplier is 16x, and the bus frequency is 133MHz (133.3 x 16 = 2133MHz). In other words, we have either to increase the multiplier or to raise the FSB bus frequency, or raise both these parameters accordingly. Contemporary Intel processors have locked clock frequency multiplier which cannot be changed (some top models allow reducing it down to 14x with the help of special power saving technologies). As for AMD CPUs, some allow doing this, I mean increasing both parameters simultaneously. However, at this point I suggest that we take a closer look at the more general case, when we overclock the CPU by increasing the bus frequency. It is especially interesting, because this way you can increase the overall system performance quite tangibly.

Why? Well, a lot of things inside a computer system are connected and synchronized with one another. For example, by raising the processor bus frequency we also increase the memory working frequency, speed up the data transfer rates and hence increase the overall system performance. However, there is another side to this picture: by overclocking both – the CPU and the memory at the same time we can exhaust the potential earlier. Very often it turns out that the CPU can be overclocked more while the memory has been pushed up to the limit. Right now only NVIDIA nForce 4 Intel Edition based mainboards allow overclocking the processor and the system memory independently. There are very few mainboards like that out there, so I assume you are very unlikely to have one. Therefore, before we get down to the actual CPU overclocking we have to make sure that our hands will not be tied up by the memory potential or something like that.