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The theory behind overclocking

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					Case Studies

INTEL 2.66GHZ PENTIUM 4 & ASUS P4P8X

80GB 7200rpm SATA hard drive provides excellent performance. A Lite-On 48X/24X /48X/16X DVD/CD-RW drive and an Alps floppy drive round out the storage options. The ATI Radeon 8500 graphics card provides video. A 400-watt Antec PSU provides power to the entire system. Overclocking The 2.66GHz managed an impressive 10194 3DMark2001 SE score. This was a 436-point improvement over the 2.4BGHz P4 and marked the first time we broke 10,000 in 3DMark without overclocking. PCMark2002 scores also showed significant increases. At 2.66GHz, the system managed a 6571 CPU score and a 7262 Memory score. Even the PCMark2002 HDD score improved over prior case studies with a 1240. By comparison, the 2.4BGHz posted a 5881 CPU score, 6919 Memory score, and 1160 HDD score. With our default readings dutifully recorded, it was time to 3DMark2001 see just how far we SE Increase could push the 2.66GHz P4. To access the 324 AMI (American Megatrends Inc.) BIOS setup utility (version 8.00.09), we pressed DEL during the POST (Power On Self Test). From the main menu, we used the left/right arrow keys to select Advanced from the tabs along the top of the screen. We then used the up/down arrow keys to select JumperFree Configuration from the Advanced menu and pressed ENTER. In the JumperFree Configuration Menu, we selected AI Overclock Tuner and used the + and – keys to set the value to Manual, which made some additional options available. Once again, with a locked multiplier, we had to adjust the FSB speed. We selected CPU External Frequency and used the + and – keys to change the value from the default 133MHz to 140MHz. We then pressed F10 to save our changes and exit the BIOS. Again, because the P4 uses a quadpumped frontside bus, changing the FSB speed in the BIOS from 133MHz to 140MHz means effectively moving from a 533MHz FSB to a 560MHz FSB (140 x

T

he theory behind overclocking is that Intel tests a sampling of chips from each wafer to see how fast they’ll run. Because quality can differ between chips in the same wafer, Intel allows for some headroom. Thus a 2.4GHz Pentium 4 may run at 2.88GHz reliably. If you get lucky, you might find a 2.4GHz Pentium 4 that’s particularly well built and will run beyond 2.88GHz. Conversely, you might get unlucky and end up with an unstable processor well before you reach 2.88GHz. So, if the theory holds true, we just might be able to reach 3GHz with our

restore the BIOS to factory default settings using the included CD-ROM. Ai NET lets you test network cable quality and diagnose problems up to 100 meters away. The P4P8X, however, features the same Intel chipset we found on the GA8IP900-L. The Intel 865P acts as the MCH (Memory Controller Hub) while Intel’s ICH5 controls most of the I/O. The ICH5 controls up to eight USB 2.0 ports, 2 SATA drives, and up to four IDE drives (two per channel). The 865P only supports 400MHz and 533MHz frontside bus speeds, but it’s less expensive than 865G or 865PE chipsets.

Intel 2.66GHz Pentium 4 ASUS P4P8X
Stock Performance Overclocked Performance Clock Speed 2.66GHz 3.11GHz Frequency 133MHz 155MHz Multiplier 20 20 VCore 1.525 1.57 CPU 6572 7576

PCMark2002

Memory 7262 7649

HDD 1240 1249

3DMark 2001 SE 10194 10518

2.66GHz Pentium 4. Like the 2.4BGHz P4 we looked at in the last article, the 2.66GH P4 is based on the Northwood core and features the same 0.13-micron design and 512KB of L2 Cache. Motherboard The Gigabyte GA-8IP900-L we used in the previous Intel case study would’ve been a very good fit with both the 2.66GHz P4 and the 2.88GHz P4 we’ll examine next. However, we wanted to provide readers with a sampling of products from other manufacturers, so we opted for the ASUS P4P8X. The P4P8X is similar to the GA8IP900-L in most respects. Rather than supporting mere 10/100 Ethernet, the P4P8X includes a 3Com chip that supports Gigabit Ethernet and the P4P8X includes an actual S/PDIF output on the motherboard’s CNR. Additional touches include ASUS’ CrashFree BIOS 2, which lets you

Interestingly enough, on many Web sites, ASUS claims the P4P8X is capable of being overclocked to 800MHz. Of course, you’d need a CPU that supports an 800MHz FSB. ASUS, however, does not mention this in the motherboard’s user manual. Like the GA-8IP900-L, the P4P8X includes dual channel memory architecture to increase data transfer rates up to 5.4GBps. The memory slots are divided into two groups of two, each slot colored either blue or black. To take advantage of the dual memory architecture, simply install two identical memory modules in the same colored slot. System Specifications While motherboards and processors change, the rest of our test system remains the same. The P4P8X still only supports PC2700 DDR SDRAM, but it did seem to get more out of our 1GB of PC3200 DDR SDRAM than the GA-8IP900-L. The

Case Studies

freeze midbenchmark. We tried increasing the core voltage once again, but even at 1.62-volts, the system remained unstable. Nonetheless, moving from 2.66GHz to 3.11GHz is fairly impressive. Final Word Although we couldn’t quite get the FSB ramped up to 160MHz, there was enough headroom built into our 2.66GHz P4 to reach 3.11GHz without anything fancier than a heatsink and fan. The FSB and CPU clock speeds increased by about 17%, slightly less than the 19% we saw in the first case study. PCMark2002 CPU scores once again tracked nicely with the clock speed improvements. CPU scores rose from 6572 to 7576, an increase of roughly 15%. Memory scores saw smaller increases of about 5% improving from 7262 to 7649, which is still better than the 20-point improvement we saw in the last case study. Even the HDD score increased (albeit not significantly) from 1240 to 1249. 3DMark scores rose from 10194 to 10518 or about 3%, which was less than we had previously seen. We saw 3DMark improvements of about 5% in previous case studies, but we didn’t manage to increase clock speeds on the 2.66GHz to the extent we did in our previous tests. Compared to the 2.4BGHz P4, however, we did see some decent performance gains. The 2.4BGHz maxed out at 2.88GHz and managed a 7023 CPU score in PCMark2002 and a 10228 3DMark score. The 2.66GHz P4 surpassed the 2.4BGHz P4’s maximum 3DMark score at 2.81GHz (10343). By the time we were done ramping the 2.66GHz P4 up to 3.11GHz, the processor was posting a CPU score 553 points higher (or roughly 7% higher) than the maximum CPU score in our last case study. 3DMark scores rose a smaller 3% over the highest score posted with the 2.4BGHz P4.
by Chad Denton

Game Port Connectors

BIOS (Award) Southbridge (Intel ICH5)

Northbridge (Intel 865P)

Front USB Headers Audio Codec

SATA Connector Ethernet Controller ATX PSU Connector

4 = 560). Changing the FSB speed to 140MHz increases the processor’s clock speed to 2.81GHz. The system showed respectable improvements in 3DMark increasing the system’s 3DMark score from 10194 to 10343. We pushed the FSB up once again to 145MHz. This increased the P4’s clock speed to 2.91GHz. 3DMark scores were actually down a bit to 10266, but the system was stable so we pushed on, increasing the FSB another 5MHz to 150MHz and throttling the processor up to 3.01GHz. We had finally managed to break the 3GHz barrier, but we didn’t have much performance to show for it. 3DMark scores were still down at 10340, three points shy of the mark we set at 2.81GHz. We began running into problems when we pushed the FSB up to 155MHz. At first the system refused to complete 3DMark with the processor running at 3.11GHz. We upped the processor’s core voltage to 1.55 but didn’t get any improvement. We

made sure the heatsink was strapped on tight and pushed the core voltage up once again to 1.57. The extra power seemed to stabilize the CPU and we were able to get a 10518 3DMark score. The Gigabyte motherboard was capable of hitting 160MHz with the 2.4BGHz P4, so we were hoping we could get the 2.66GHz up to 3.21GHz on the P4P8X, but it wasn’t meant to be. Increasing the FSB another 5MHz caused 3DMark to

Overclock Comparison 3DMark2001 SE
Intel 2.8GHz Pentium 4 (533MHz FSB) Stock Performance 10230 Overclocked Performance 10568 5 Intel 2.66GHz Pentium 4 (533MHz FSB) Stock Performance 10194 Overclocked Performance 10518 Intel 2.4BGHz Pentium 4 (533MHz FSB) Stock Performance 9748 Overclocked Performance 10228


				
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