Recalling our last-week’s overclocking experience with the EPoX 9NPA+ Ultra we attempted to raise the frequency of the clock generator to 240MHz at once, but the mainboard wouldn’t work. It wouldn’t work at 230MHz, either. That was suspicious already, but we went on reducing the frequency of the clock generator until the mainboard passed the POST procedure successfully.
We would like to note that it is very easy to experiment with overclocking on Chaintech VNF4 Ultra VE mainboard: if it can’t start up, it automatically returns the BIOS Setup settings to their defaults and restarts in the safe mode. That’s why we didn’t have to use the Clear CMOS jumper even once in our tests.
As we found out soon, the maximum frequency of the clock generator at which the mainboard can get past the POST is 221MHz. The overclocked system remains perfectly stable in Windows XP, too. It means those 221 megahertz is not the top limit, but overclocking above this point is limited by some other factors.
We know from our earlier tests that the main obstacle preventing you from raising the clock generator frequency higher is the HyperTransport bus, which frequency becomes too high. We ran some tests with the HT multiplier set 5x, that is when the clock generator frequency equaled 221MHz, the HyperTransport bus frequency grew up to 1105MHz against the nominal 1000MHz.
So, we just reduced the frequency multiplier of HyperTransport to 4x, but unfortunately it didn’t affect our overclocking in any way. The mainboard still refused to boot Windows up at more than 221MHz on the clock generator speed. A further reduction of the HyperTransport bus frequency multiplier couldn’t help us get past this barrier, either.
Next, we tried to tweak other mainboard settings, but neither higher voltage values, nor different PCI Express frequencies helped us. That is, a clock generator frequency of 221MHz is the maximum you can get using the BIOS Setup of the Chaintech VNF4 Ultra VE mainboard. That’s little of course, but you can’t do anything about it.
We could have stopped at that dissatisfying result, but then decided to check out one wild idea: maybe the Chaintech VNF4 Ultra VE is better overclocked from the OS, rather than from the BIOS Setup? We know at least two utilities that could be helpful in this case. The first is the well-known nTune from NVIDIA.
The second program is ClockGen from Franck Delattre: its new version supporting nForce4 Ultra chipset has recently appeared on www.cpuid.com:
We made up our mind in favor of ClockGen as it offers more functions and allows raising the clock-generator frequency above 250MHz which is the limit for nTune. You may imagine our surprise as we saw the Chaintech VNF4 Ultra VE overclocking far above 221MHz from the Windows! Our special thanks immediately go to ClockGen and its developer!!!