I recently built a new system, but I have no experience overclocking and am not sure how to best balance heat under load and performance.
So far, the only performance-oriented configuration changes I've made are setting the appropriate RAM latency settings to match the specs of my Kingston HyperX (down to 7-7-7-20) and playing with the CPU multiplier and ATi's built-in Overdrive tool.
I'll list my hardware first, then go over what I'm hoping to accomplish and my experiences thus far. Any advice would be greatly appreciated. My top overclocking concerns, in order, are safety and stability (I want a 24/7 set and forget setup that will not severely decrease the lifespan of my components), GPU-bound gaming performance, CPU-bound general performance. My current plan is to push my GPU as hard as I can without stability or heat issues, and see what you guys think about CPU overclocking.
Case and cooling: Antec Three Hundred w/ stock fans (2x120mm) - have 3x120mm Apevia case fans sitting uninstalled since they seem to have given me the wrong screws >.<, stock heatsink on the CPU
CPU: AMD Phenom II 550 Black Edition - 2x3.1GHZ
GPU: XFX Radeon 4850 1GB - 625/993MHz
RAM: 4 (2x2) GB DDR3-1333 Kingston HyperX
Mobo: MSi 770-C45 (AM3/DDR3/SB710)
Software: ATI Catalyst 9.9, Windows 7, 64 bit.
What I've done so far:
My CPU defaults at 200MHz x 15.5. I haven't messed with the voltage or FSB, but I have set the CPU multiplier as high as 18 with no stability issues and I've run it at 17x (3.4GHz) for a while... The CPU rarely tops 50 under moderate load and seems to stay stable between 55-60C under sustained heavy load. However, I've turned it back to stock settings for now, as it seems CnQ cannot be enabled with a modified multiplier. My CPU runs at a minimum of around 40-42 at full speed (doesn't seem to change by more than 1-2C overclocked versus stock, which is a good sign, right?), whereas with CnQ under low load when it drops all the way down to 4x it can get to around 32-35C. That's a noticeable temperature difference when it's, for example, on downloading a large file overnight. So far, I'm more than happy with performance and stability, but if I can't enable CnQ or some alternative so that I can reduce heat during long low-load periods without having to reboot and mess with BIOS settings every time I want to switch back and forth, I'm not sure it's worth the sacrifice. I haven't benchmarked it, but I don't really notice the increased performance from 10% more CPU cycles, as the primary resource-bound task I do is gaming which is GPU bound at any reasonable resolution these days. I haven't looked into unlocking the other cores beyond changing ACC to auto and seeing if it did anything (it didn't cause CPU-Z to report any extra cores so I gave up and set it back). So, that's where I'm at with the CPU.
As for the GPU, as I said, I've used Overdrive but nothing else. Right now, I have Overdrive set to 685(+60)MHz for the cores and 1055 (+62)MHz for the RAM, up from 625/993 stock. I was able to run it higher before running into stability problems but I'm not sure exactly where the limit is, so I aimed on the conservative side (it definitely starts to have stability issues at 700/1100, and if I recall correctly it appeared to be the RAM clockspeed that was causing the most trouble). I also set the fan to run at 85% at all times - it's a LOT louder at 100% and seems to keep the temperature stable under load at 85, plus I figured running it at full speed all the time might not be good for the fan's longevity. It hovers around 40 when downclocked and not in use. Under load when Overdrive kicks in, it seems to top out in the low 60s - usually right around 60 but occasionally climbing closer to 65.
The only other thing I've done is change the latency settings for my RAM. No other BIOS configurations or driver settings have been altered.
My top 3 questions at this point would be:
1. Is there any way to overclock my CPU while either keeping some degree of CnQ functionality or finding some alternative?
2. Is there a better tool for GPU overclocking than the built-in Overdrive software?
3. How should I go about testing OC settings for my GPU? Overdrive will pass just about any settings I throw at it, even ones that prove unstable under actual use, but it can take a while for these problems to pop up simply by gaming. Is there a good stress test to rapidly diagnose problems there?
4. Any other hardware I should be OCing? Any other software-based tweaks I should know about to improve GPU performance beyond keeping up to date with drivers and setting Overdrive as high as I can?