It has been a while since I did any overclocking of CPUs. I got into a little bit in the heyday of it all, but didn't have the time and couldn't be bothered wasting the money on the exotic cooling systems available to get more performance out of my CPU.
After all, CPU prices fall quite quickly and cooling gear is more costly than CPUs. Not to mention that the cooling gear you buy today won't (or probably won't) fit or have adapter plates etc available for the CPU you replace it with in a year or so.
The approach of unbridled overclocking is a waste of money in my opinion. However, if that's your hobby, if it's your thing then that's just cool. It's not my thing.
For me, overclocking is about using older or lower cost hardware and making it go a little quicker so that it's able to give more than the task at hand needs. After all, why drive a 1.3 litre buzzbox when a 1.8 will use about the same fuel if it's properly tuned and carefully driven, but will give you ever so much more performance if and when you need it. Make sense?
There's one machine I tend to use the most just for surfing, e-mails, quotes, watching videos over my shoulder when I'm supposed to be working - just a general duties machine. Here's the config:
* AMD Opteron 144 CPU, stock 1.8 GHz
* Zalman CPU cooler with radial fins and a 90 mm fan
* 2 Gb DDR266 RAM
* Asus GTX260 overclocked display card
* 24" Fujitsu widescreen LCD
* 800 W modular power factor corrected PSU (sorry, forgot what kind and I can't be bothered to open the case right now - however, the fan is variable speed and 'runs on' until a temperature set-point is reached when the machine is switched off in software).
* 1 x 120 Gb PATA HDD for Boot
* 1 x 320 GB SATA HSS for my home folder
* 1 x 90 mm case fan
* CD-R burner
* DVD + - everything burner
* and a whole heap of other stuff hanging off the USB ports.
Yep - a rather plain office machine with a quick-ish graphics card. Legacy hardware for the most part.
As I mentioned, the CPU at stock runs 1.8 GHz. It's no prize winner - it's just fine for most day to day stuff under Ubuntu.
However, I wanted a little more grunt and didn't want to spend any more on it. So, a bit of quick overclocking in BIOS and we're on our way. I've boosted it to 2.3 GHz which is mild compared to some more serious Opteron 144 overclockers, however, I didn't want to spend more money on exotic cooling. The trick to remember is to set the overclocking to asynchronous. There's a big chance that you can drive the CPU and memory harder but that the bus may not be able to take as much pushing. Experiment at your own peril. I will.
The Zalman cooler has an external fan speed controller. Like most people, I believed faster is better so had it cranked up to maximum speed - about 2500 rpm. When the fan is running at maximum speed, initially the temperature is stable. I just installed some temperature monitoring software which I'll talk about in another article. I wanted to see what difference fan speed made to cooling.
With the fan at maximum speed and the CPU driven at 100% for an hour, the temperature peaked at 60C. However, dropping the fan to 1400 rpm the temperature fell to 38C after about ten minutes at about 25% load. Woot!
However, as soon as you put the CPU and GPU under load, the temperature will climb again. After half an hour the CPU temperature was 59C and stable.
As I've mentioned before, I've been twiddling with overclocking the display card and have mentioned nvclock-gtk. It has a setting which allows the fan duty cycle to be adjusted manually. I had set that at around 80% thinking faster fans, better cooling, etc. Wrong. Dead wrong.
Allow the fan speed to remain under automatic control. The duty cycle will vary as it needs. The result? 72C with the fan running fast and 63C with the fan on automatic. The duty cycle runs between about 35% and 85% under 100% load conditions on the CPU and the GPU but it remains pleasantly cool.
Result? Dropping the CPU fan speed and setting the GPU fan speed to automatic gives lower temperatures. Here's the results:
* Core 0 = 59
* CPU fan = 1394 rpm
* Sys Temp = 50C
* CPU Temp = 60C
* AUX 2 Temp (mobo) = 60C
* GPU = 67C
* Display Adapter Ambient = 55C
* both HDD = 52C.
In real terms, the air flow needs to be improved to cool this machine more effectively.
For me, all of the above is great news. My workstation and another server are under my corner desk here in the office. The highest temperature recorded under the desk in summer was 73C. BBQ pork legs - my legs!! There's no chance I could slide some fun under there.
I'm happy to help you get somewhere with a result for your rig. Comment or e-mail and I will help you.
Peace out...
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