For our tests, we used an ASRock 939Dual-SATA2 motherboard that supports AMD’s Socket 939 natively and Socket AM2 through a CPU upgrade daughterboard. This is a unique feature that a handful of ASRock boards offer, but the basic procedure for minimizing the CPU bottleneck in any old AGP system is the same: buy a faster CPU or overclock what you have.
We looked around locally and found a used AM2-based Athlon 64 X2 4200+ for $45. For sure, we could have worked with our existing Athlon X2 3800+, but we wanted something with a higher clock multiplier so that we wouldn’t have to push it as hard to reach our goals. Besides, the price was right and this CPU could serve our overclocking purposes nicely.
Plan on spending $100 for an AGP graphics card upgrade to kick some life into your old system, and another $50 for an overclockable CPU if your processor is an aging single-core model or an overclocking dud.
With a 2.2 GHz stock clock speed, the Athlon X2 4200+ isn't the fastest AM2 CPU our motherboard can handle, but it should overclock to 2.6 GHz or slightly beyond with a stock cooler, which roughly matches Athlon X2 5000+ specifications. We could have spent a lot more on a faster processor, like an Athlon 64 FX-62 at 2.8 GHz. But it's not really worthwhile, since we don't want to invest too much in the old system. Remember, we're overclocking to get the most out of our old hardware. It doesn’t make a lot of sense to spend enough cash to build a new one.
In our particular case, since we couldn’t find a Socket 939 candidate fast enough for our needs, we settled on an AM2-based model. Because of this, we also had to shift from DDR to DDR2 memory, since the ASRock 939Dual-SATA2 requires DDR2 on its AM2 daughterboard. This isn't typical of what most people will have to deal with, but the performance should demonstrate a best-case scenario compared to our last article. Remember, in part one, we employed a hodgepodge of memory DDR memory modules in order to hit 2GB, resulting in a lower clock. We accepted this scenario because it accurately represented the mixing and matching one might experience with an older system. After our new benchmarks are run, we'll have the opportunity to compare results. These two extremes should give us a good indication of the range of performance one can expect between a system with slower RAM versus a faster system with memory running in dual-channel mode.
Installing a CPU on a daughterboard isn't something we do every day, but the procedure was simple and it worked well enough. Kudos to ASRock for manufacturing a motherboard with literally years of longevity.
With everything running smoothly, it came time to overclock the beast. We're not looking for a extreme tweak here, but we want to achieve a nice boost that will provide meaningful benefits in our gaming tests. Additionally, our build is only valid if it won't cause overheating with the CPU running 24/7. We targeted an overclock of 2.6 GHz, which is a 400 MHz increase from the stock Athlon X2 4200+. Since the Athlon X2 5000+ runs at 2.6 GHz and has the same architecture and cache configuration as the Athlon X2 4200+, the resulting performance should closely demonstrate what an Athlon X2 5000+ would enable.
To get this speed, all we had to do was alter a few settings in the BIOS. We increased the reference clock to 237 MHz, up from the stock 200 MHz. With the Athlon X2 4200+’s multiplier of 11x, this gave us a CPU clock speed of 2,607 MHz. For stability's sake, we didn't need to add any CPU voltage, but we lowered our HyperTransport multiplier to 3x from the stock 4x, giving us a HyperTransport speed of 948 MHz after the overclock (very close to the stock 1,000 MHz). We also played with the memory speed and set it to 333 MHz in the BIOS. Since this sets the memory speed to 333 MHz at the stock FSB speed of 200 MHz, our actual memory frequency ended up as 372 MHz (744 MHz DDR). All of these settings are quite conservative, as we want to demonstrate something that an average user can achieve without difficulty.
There is one more clock speed we could tweak: frequencies on the new AGP Radeon HD 4650. Unfortunately, there’s not much to report here. The beta drivers included with the card didn't support ATI’s Overdrive feature. With the nice non-reference cooler Gigabyte included, it's a shame we weren't able to unleash the card's overclocking potential. Perhaps in the future, the AGP Radeon HD 4650 will be supported by AMD's Catalyst drivers and Overdrive.