The remaining hardware common to both series of tests consists of the following:
Biostar TForce 8200 A2+ motherboard (nVidia 8200 chipset)
2x1Gb OCZ Titanium DDR2-800 @ 3-4-4-8
Swiftech H20-220 Compact water cooling
eVGA GTX 260 192sp
3x74Gb WD Raptor HDDs in RAID0
CPUZ shows both the stock and overclocked states for the Phenom 9850 X4 BE. This particular sample was an early week 11 of 2008, which despite being the most recent B3 revision core, was not a very good overclocker. Only 500Mhz separated the maximum stable overclock of 3.0Ghz @ 1.4v from the stock 2.5Ghz @ 1.3v spec. As you will notice, this motherboard under-volts slightly by 0.02 - 0.025v. Although more voltage was applied, and temps remained good, the 9850 simply didn't respond with any more speed.
The Phenom II 720 X3 BE by comparison starts at 2.8Ghz @ 1.325v, slightly more than the older Phenom, but increases all the way to 3.7Ghz @ 1.575v, nearly a full 1Ghz overclock. Speed scales very nicely with voltage increases, with 100Mhz increments requiring roughly an additional 0.05v for every step above 3.2Ghz. The 720 then hits a brick wall at 3.7Ghz, and no amount of voltage, even up to 1.7v, will make 3.8Ghz stable enough to boot Windows. In fact, once above 1.6v the chip just becomes more unstable when more voltage is applied.
Now let's run some tests and see whether the new X3 Phenom II at 2.8Ghz and 3.7Ghz can outpace the old X4 Phenom at 2.5Ghz and 3.0Ghz despite having one less core.