AMD Opteron 1212 2.0Ghz Santa Ana Dual-Core
Stock AMD Copper Heatpipe Cooler
2x1Gb OCZ SLI DDR2-1066
With the processor's 10x multiplier ceiling, raising the reference clock will be the primary means of overclocking. The Opteron 1212 Santa Ana core is nearly identical to the upper echelon Windsor X2, a 90nm die size with 2x1Mb of L2 cache, and the latest F3 stepping. Without touching the 1.3 vcore, and dropping the memory setting down to 400, it is possible to increase the reference clock all the way to 270Mhz.
At 2700Mhz and still stock vcore (slightly overvolted) the CPU is hardly breaking a sweat, with temps running only in the 30's. Likewise the memory is barely above its rated speed and the HyperTransport has room to grow as well. Unfortunately this appears to be the highest attainable frequency with the J&W RS780. Increasing the reference clock just 5Mhz more causes failed POSTs roughly half the time the machine is booted. By 280 the system will not POST at all.
What is puzzling about this apparent wall is that no matter what is tried, whether lowering the HT multi or memory frequency, or increasing the CPU, DDR, NB, SB or HT voltages, no clock speed above 270Mhz will boot reliably. And yet when 275 does work, it will load Windows and run benchmarks without any problems, the issue does not reoccur until the next restart. I have seen other chipsets perform similarly, topping out on the bus frequency in the 260 - 280Mhz range, so perhaps it is a limitation of the 780G. Or possibly being a micro ATX board with an admitted inability to handle high wattage CPU's, the stability of the system's power circuitry comes into question, despite J&W using an 8-pin EPS connector for the auxiliary +12v.
The 780G is one of the few 700-series chipsets supported in OverDrive, AMD's overclocking utility. They have just recently released a new 2.1.2 version, denoted by its red and black color scheme. I think I actually prefer the green and white of the old interface, it was at least easier to read. Whichever version you choose however, not only gives the flexibility to adjust various clock frequencies, voltages and timings, it also offers a complete snapshot view of the current system properties. OverDrive is not without its faults however, whether the result of the board manufacturer or particular BIOS used, I found that the software could not read certain settings correctly, and thus I was hesitant to do any overclocking through it at all. I've never had much luck with software overclocking anyway, and prefer the solidity of the BIOS.
The onboard graphics can be overclocked as well, and I was able to reach 650Mhz on the IGP vs. the standard 500Mhz core. I also tested the performance difference of the UMA-only setting, where the graphics frame buffer is allocated from system memory only, and compared that to the dedicated 64Mb in both a 1:1 ratio and 1:4 ratio of SidePort to system memory. I used a standard benchmark graphics test to measure frames per second for each setting. The best performance was obtained surprisingly when set to SidePort + UMA and left to Auto allocate frame buffer size. Of course overclocking the core frequency also helped boost FPS.
Let's wrap things up with a few final thoughts and conclusion.