This pertains to CPU overclocking, just a few tips I've learned over time. Before this though, I want to make sure everyone knows that voltage is force, and you want to avoid using voltage increases as much as possible, since aside from using more power and throwing off more heat, it's just not good, it increases the stress on the component. There are ways to get speed from a CPU without ramming voltage increases down its throat.
1) Always use BIOS to overclock. Yes AMD Overdrive may be convenient, but the extra few seconds for a reboot is worth it. From Run (Windows + R) type "msconfig" and change it to Diagnostic Startup (e.g. Safe Mode) to keep from having to bring up the menu each time, restart, and enter the Blue Hell known as a BIOS, although some UEFI's are getting nice now.
2) Most may think this is stupid, but what I've always done is on my Vcore I'd set it high at first, 1.45v on Phenom II, don't know about Bulldozer, maybe 1.4v, most good quality boards will have a Vcore overvolt protection to keep you from going way to high, and working it down from there after I get a speed I'm happy with. Most will tell you to keep it at stock and work up from there a tenth or so from there, but by setting it high first it eliminates the speeds which will never be stable, saving you a headache.
3) Vcore is not always the answer to stability problems. Most boards have a setting called "CPU VDDA" which has to do with voltage under load. Increasing this to 2.75v (some say 2.8 or 2.85v, but I've found 2.75v to be optimal) will boost the CPU voltage under load (slightly), helping to keep it stable under load while letting it run with less voltage under low load conditions (web browsing, for example).
4) HT and CPU/NB are important settings too. Most AMD CPU's are designed to be able to run with a HT speed of 5200MT/s or higher, yet many boards will default to the old 2000MT/s (4000MT/s DDR as the HT link is bi-directional). Increasing the HT to 2600MT/s, usually not requiring any increase in voltage, will reduce access times. Same thing with CPU/NB, increasing this to 2800mhz (mine will not stay stable any higher but yours might), not requiring any voltage boost usually, also reducing access times, most easily measurable on a memory benchmark.
5) ECC. In your BIOS somewhere, usually under CPU Settings, will be an option to set ECC. Now, most all of us will use non ECC DRAM modules, as ECC modules are expensive, not as fast as non ECC modules, and intended for servers, so you can ignore those, but there will be 3 options for L1, L2, and L3 Cache (sometimes the L1 cache will be split into Instruction and Data as well). Set these to 2.56µs. Why? Because overclocking will cause errors, same way overclocking a GPU just a bit to far causes artifacts, as artifacts are just visual representations of corrupted data. Having ECC on can catch these errors. It may not let you get any more speed out of your overclock, but it can help you get the same speed at a lower voltage.
6) Last thing I can think of is that getting the most out of your system is not always the way to do it. I can get 4ghz out of my CPU, but it takes 1.42v. However, I can get 3.8ghz (a paltry 400mhz boost I know) at just 1.389v with no noticeable reduction in performance. Why? It's because with the resolutions common today, 1920x1080 and above, that taxes your GPU harder than your CPU. Sure you don't have that ePeen factor, and yes a 5ghz i7 will push out more frames, but ask yourself these questions: Do I get a number of frames equal to my refresh rate (exception: plasma TV's used as a display, as plasma has a 600hz refresh rate, you're not going to get 600fps)? Does my GPU monitor tell me that my GPUs are running in the high 90s or 100% yet Task Manager shows that all my CPU cores used by this game are at 50 or 75%? Is all this extra heat and power usage worth the extra couple hundred mHz? If you answer Yes, Yes, and No, then you've learned what I consider to be the most important lesson in overclocking, which is to find the most optimal balance of speed and power (and therefore heat as well), not to push every component to the absolute limit of what it can do.
Think of your computer like a car. Yes you pile on all these performance parts such as Flowmaster exhaust and Edelbrock intakes, perhaps even a supercharger or turbocharger, but you don't want that car, when you drive it, to feel like it is on the edge of going up in flames or going to shake itself apart, you want that car to go fast, yet feel stable and controlled, you want to be able to drive it for years, not give it a shot of nitrous and have to rebuild the engine after every drive.
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