What do you usually mean when you say "the processor is chasing well"? For example, I understand "at least" well at least 1.5 times overclocking. That is, for example, many Athlon XP 1700+, some Pentium 4 2.0 on Northwood core, etc., are well chased. As it was already noted several times, the younger processors in families, which are based on the most modern processor cores, have the greatest appeal when overclocked. That's why we paid special attention to the recently appeared Pentium 4 2.4C processors, designed to operate at 800 MHz, but until recently there were no "overclocked" processors among them. We achieved an increase in the frequency of 40% and even sometimes 42%, but until the cherished mark of 50%, we have never reached such a goal. However, it was so before.

The hero of today's note was able to finally break my bad opinion of the Pentium 4 2.4C. In my hands, in the end, got a processor that could earn at a frequency of one and a half times the nominal. In appearance, the next Pentium 4 2.4 GHz I received was not anything:

Like other Pentium 4 2.4C, this processor had an S-spec SL6WF and used a supply voltage of 1.525V. The country of manufacture of the processor is MALAY, and, according to Doors4ever theory, this processor should have a good overclockability.

I installed this processor in my testbed, which consists of the following parts:

The processor is Intel Pentium 4 2.4C;

The cooler is boxed;

ASUS P4P800 Deluxe, BIOS version 1008;

Memory OCZ PC3700 - two modules of 256 MB;

ATI RADEON 9700 PRO video card, Catalyst 3.4 drivers

It turned out that without problems (that is, without increasing the supply voltage), this CPU is able to work not only with a FSB frequency of 275 or 280 MHz, but it can also work at an incredible FSB frequency of 300 MHz.

My attempts to crash the system with such acceleration were not successful - all tests for stability were successfully passed. Thus, the described Pentium 4 2.4C was accelerated 1.5 times to the frequency of 3.6 GHz without increasing the supply voltage and using the absolutely ordinary air cooling represented by the boxed cooler!

I must say that the frequency of 3.6 GHz for the processor on the core of Northwood looks incredible. The older model Pentium 4 now has a frequency of 3.2 GHz, and the next model with a frequency of 3.4 GHz will have a new 0.09-micron core Prescott. Thus, Intel unambiguously makes it clear that 3.2 GHz is the maximum for Northwood. But, having entered into a dispute with Intel, we were able to refute their concept of the limiting frequencies for the current core.

Another important thing that I had to face when overclocking the Pentium 4 2.4C is that increasing the FSB frequency to 300 MHz (or in quad Pumped Bus terms increasing the processor bus frequency to 1200 MHz) imposes additional requirements on the equipment used in the system . First of all, to achieve such a high result requires a competent motherboard, which can function stably at a FSB frequency of 300 MHz. I checked two boards - ASUS P4P800 and ASUS P4C800: both of them could pull the FSB 300 MHz clock. Due to the features of the i865 and i875 chipsets, the frequency of PCI and AGP can be fixed with increasing bus frequency. Therefore, there were no problems with either the IDE controllers or the video card. But with memory had to tinker.

Let me remind you that the i865 and i875 logic sets have for the memory frequency, in addition to 1: 1, and the lowering coefficients (relative to the FSB) 3: 2 and 5: 4. As a result, if the FSB bus frequency is higher than 200 MHz, we theoretically can use not only overclocker memory, which operates at out-of-band frequencies, but also the usual DDR400 SDRAM. Here is a plate showing which frequencies on the memory can be obtained at different bus frequencies:

FSB frequency

DDR266 (FSB: MEM = 3: 2)

DDR333 (FSB: MEM = 5: 4)

DDR400 (FSB: MEM = 1: 1)

200 MHz

133 MHz (DDR266)

160 MHz (DDR320)

200 MHz (DDR400)

210 MHz

140 MHz (DDR280)

168 MHz (DDR336)

210 MHz (DDR420)

220 MHz

147 MHz (DDR293)

176 MHz (DDR352)

220 MHz (DDR440)

230 MHz

153 MHz (DDR306)

184 MHz (DDR368)

230 MHz (DDR460)

240 MHz

160 MHz (DDR320)

192 MHz (DDR384)

240 MHz (DDR480)

250 MHz

167 MHz (DDR333)

200 MHz (DDR400)

250 MHz (DDR500)

260 MHz

173 MHz (DDR346)

208 MHz (DDR416)

260 MHz (DDR520)

270 MHz

180 MHz (DDR360)

216 MHz (DDR432)

270 MHz (DDR540)

280 MHz

187 MHz (DDR373)

224 MHz (DDR448)

280 MHz (DDR560)

290 MHz

193 MHz (DDR386)

232 MHz (DDR464)

290 MHz (DDR580)

300 MHz

200 MHz (DDR400)

240 MHz (DDR480)

300 MHz (DDR600)

As you can see, in theory, even if the FSB frequency is increased to 300 MHz, you can limit the usual DDR400 memory, if you set the frequency factor on the 3: 2 memory bus. In practice, everything turned out to be quite different. With a frequency of 300MHz FSB and a selected ratio of 3: 2 memory, the system could not work with conventional DDR400 modules. The fee simply did not start. Only the overclocking modules OCZ PC3700 were able to save the situation, with them the overclocked system worked steadily. But that's what this problem is, it's still a mystery.

One possible explanation for the inoperability of DDR400 memory with a FSB frequency of 300 MHz is that the chipset, thinking that the system uses DDR266 SDRAM (because the 3: 2 reduction factor implies the use of this memory), uses some more aggressive memory settings that modify Directly in the BIOS Setup can not. In this case, it becomes clear why with increasing the FSB frequency to 300 MHz, you can not use conventional DDR400 SDRAM.

An indirect confirmation of this theory is the fact that the performance of the memory subsystem with a FSB frequency of 300 MHz and a memory frequency of 400 MHz is significantly higher than at a FSB frequency of 200 MHz and a memory frequency of 400 MHz. Although in both cases the throughput of the processor-memory bus is 6.4 GB per second, the results of SiSoft Sandra in both cases (with the same timings being set) differ drastically. Here, for example, the result of the measurement at a FSB frequency of 300 MHz:

But what happens when the FSB frequency is 200 MHz:

Although in theory, indicators should be the same, there is a difference of about 15%, which, I must say, a lot.

In general, you want to drive a Pentium 4 2.4C - store quality memory. And this processor turned out to be rather not bad and now it will take a worthy place on the overclocker board next to the Athlon XP 1700+ and others.