Overclocking: More Voltage, Higher Clocks
Cranking Things Up a Notch
We curbed the limits of our Core 2 overclocking to best-represent the maximum frequencies value-seekers with this hardware will probably be using long-term. But the enthusiast in me just couldn’t stop with little or no voltage increase to these E0-stepping chips, knowing I may never again set up this aged platform for testing. Plus, I had already put a considerable amount of tweaking time into this very hardware a few years back, and still had notes handy detailing how high my chips would go, and the voltages required to get there.
At 1.45 V in the BIOS, 1.416 V at idle, or 1.384 V under load, this Core 2 Duo E8400 is stable at 4.5 GHz. It’s seen a fair amount of testing at these settings, but I’d drop voltages and top out in the 4.2-4.3 GHz range for daily use. At this high of a front-side bus frequency, I limited tweaking to CPU clock speed, and didn’t maximize the RAM configuration, running DDR2-1000 @ 5-5-5-15 timings. The Common Performance Level was left at default tRD 09. My success in RAM tweaking on this platform has come with 1 GB sticks of CAS 4 DDR2-800, and with this particular 4 GB kit, voltage requirements have far outweighed any gains.
I don’t like to push Core 2 Quad voltages as high, but would quickly reach the limits of this fairly modest Xigmatek HDT-S1283 air cooler anyway. The Q9550 is stable at 3.7 GHz set to 1.3625 V in the BIOS, resulting in 1.240 V under load. Again for daily use, I’d drop voltage a tad and be in the 3.6-3.65 GHz range, while keeping an eye on temperatures during those hot summer months. This front-side bus results in DDR2-1045 data rates, and with a little bump in voltages, I was able to further tweak the Common Performance Level to tRD 07, boosting memory bandwidth up to 8.36 GB/s.
To be honest, I originally had no intention on publishing this data, and only ran a few applications just for my own fun and knowledge. But the deeper I got into this, the more the information seemed worthy of sharing. Pushed to 4.5 GHz, the Core 2 Duo E8400 is able to match the single-threaded performance of Core i5-3570K at its 3.8 GHz Turbo Boost frequencies. While we know our K-series Core i5 itself has plenty of headroom for higher clock rates, we are still impressed by how well our four-year old E0 stepping Wolfdale-based scales. While the Core 2 Quad's gains are less impressive, we are eager to jump to the next page and see the impact during gaming.