RSS Feed

HCW Tech Blog

For the latest info on computer hardware, tech, news, video games, software tips, and Linux, check out our new improved front page: HCW Tech Blog

Reviewed by: Carl Nelson [08.27.06]
Manufactured by: OCZ Technology



Being the first time really overclocking an AMD processor with DDR2, I wanted to make sure I got things right. I know AMD processors have really wacky memory dividers, sometimes cutting the ram speed down significantly. For instance, a standard 200 MHz HTT clock with a 12x multiplier will yield a proper speed of DDR 800 (CPU speed / 6). A CPU with a 10x multiplier will yield the same (CPU speed / 5). However, set the multiplier to 11x, and you will have problems.

The memory divider is set to the amount that will allow the ram to run closest to its setting, but not over. In the case of 11x, it will be CPU / 6. So if you have an Athlon64 X2 4200+ or 4400+, your CPU is running at 2.2 GHz, and your "DDR2 800" memory is running at 366 MHz, or "DDR2 733".

Long story short, we only used the CPU's standard 12x multiplier, and 10x.

4-4-3-15 Overclocking

Overclocking began with standard 4-4-3-15 timings. The OCZ SOE Urban Elite PC2 6400 was installed in a Foxconn C51XEM2AA-8EKRS2H-WTF (NFORCE 590-SLI) with a retail AMD Athlon64 X2 4600+ with retail cooler. The CPU runs at 2.4 GHz (200 HTT x 12). I bumped the DDR2 voltage to 2.2v and the CPU to 1.6v to get things going.

I've never overclocked this CPU since buying it for our Core 2 Duo Review last month, so it was time to see how far I could take it with stock cooling. I left the multiplier at 12x, and started bumping the HTT up, using NVIDIA's excellent nTune software. 210... 220... 230... All yielded stable performance. At 240 HTT, the system hard-locked. On the next reboot, I set the HTT to 235 and ran two instances of Prime95. No problem! To be sure, I left them running overnight. No problem! 

With stock cooling and the highest multiplier, I was able to bring the 2.4 GHz 4600+ up to 2.82 GHz. This DDR2 800 memory was running at DDR2 940 while maintaining tight 4-4-3-15 timings.

At this point, I suspected that I reached the CPU's limit with current voltage and cooling, so I lowered the multiplier to 10x and immediately went for a 240 MHz HTT. Unfortunately Prime95 would crash the system, so I have determined that this memory's top speed with 4-4-3-15 timings is DDR2 940.

5-5-5-15 Overclocking

For the folks who want the highest FSB possible, and care less about memory latency, I set out to find out just how far I could push this ram. The board itself has been tested to go as high as 330 MHz HTT, so I would have no problems finding its limits.

After determining that 2.82 GHz was indeed not the fastest this CPU could go, and that I was limited by the ram at 4-4-3-15, I went back to a 12x multiplier with more loose 5-5-5-15 timings. Eventually, I was able to push the HTT to 260 MHz, but Prime95 would not run longer than about 10 minutes. This meant that the DDR2 800 memory was running at DDR2 1040, and the CPU reached 3.12 GHz. That's quite the jump from 2.4 GHz, on stock cooling!

This time I really do think I found the CPU's limit with stock cooling, so once again I lowered the multiplier to 10x, and went back to the 260 MHz HTT. This time, with the CPU running at 2.6 GHz, the system was perfectly stable while running Prime95 for 2 hours. I am convinced that the limit of this CPU is somewhere between 2.82 and 3.12 GHz, at least with stock cooling.

I could not get the ram to remain stable at anything over DDR2 1040 with a reasonable bus speed, so that appears to be the limit of this particular pair of modules. Remember, overclocking results WILL vary, and this kit is only guaranteed and warrantied to run at speeds of DDR2 800. That being said, you could very well get similar results as I, give or take a few MHz. Still, if you want a guaranteed memory overclock, look elsewhere.

Next Page: (Performance; Conclusion)