As for the CPU overclocking options, they are the following:

• The frequency of the clock generator forming the CPU frequency can be adjusted between 200 and 456MHz with 1MHz increment;
• The frequency of the PCI Express bus can be independently adjusted between 100 and 150MHz with 1MHz increment;
• The CPU frequency multiplier can be adjusted manually (reduced below the nominal value). The minimal value is 5x;
• The processor Vcore can be increased up to 1.75V with 0.05V increment;
• The memory voltage can be selected manually. DIMM slots can receive from 2.6V to 2.8V with 0.1V increment;
• The chipset voltage can be increased from the default 1.5V to 1.8V with 0.1V increment;
• The voltage on the HyperTransport bus can be adjusted between 1.2V and 1.5V with 0.1V increment;
• The parameters responsible for the working frequency and width of the HyperTransport bus can also be adjusted. The frequency of this bus is set with a multiplier (relative to the clock generator frequency), which can be set to 1x, 2x, 3x, 4x, and 5x. The width of the bus can be set to 8 or 16 bits in any direction.

All in all, Gigabyte GA-K8NXP-SLI boasts a pretty good set of overclocking friendly options. However, the supported ranges of some selected parameters arouse some questions. I am talking about the voltages in the first place. If the 1.75V maximum for processor Vcore is enough in most cases, then the maximum voltage for the DIMM slots is quite low: only 2.8V. To be honest, this value is simply ridiculous according to the today’s standards. There are a lot of high-speed DDR-SDRAM modules out there that require higher voltage even in the specification. What overclocking can we talk of in this case?

So, even though Gigabyte GA-K8NXP-SLI has become very much like an overclocker product, there are quite a few things that spoil the impression and need to be taken care of before we rank it high.

But this is not the final verdict yet. Let’s check how this mainboard is going to behave during real overclocking experiments.

For our tests we assembled a system on Gigabyte GA-K8NXP-SLI mainboard with an Athlon 64 3800+ processor on Venice core. First of all we decided to see how far up could the clock generator frequency go, before the mainboard would lose stability. For this test we reduced the clock frequency multiplier to 6x and dropped down the memory frequency, so that the board could be the only one to affect the overclocking results.

With the nominal HyperTransport multiplier of 5x we started experiencing problems at 240MHz frequency already. However, it is a known fact that nForce4 SLI based mainboards do not feel quite comfortable when the HuperTransport frequency exceeds 1000MHz. So, you have to reduce the corresponding multiplier to avoid this issue. This was exactly what we did: HyperTransport multiplier was reduced to 3x. After that we were pleasantly surprised, as our Gigabyte GA-K8NXP-SLI remained stable until the clock generator frequency reached 350MHz. In other words, the mainboard copes perfectly well with the clock generator frequency increase.