Explain to me overclocking and underclocking....

[Justitia]

Explain to me overclocking and underclocking....

I have been reading these forums for a couple of months and I thought I would glean what it meant over time ...but I have not.

I have searched but I have not come up with a thread that I can understand.

Maybe just a basic over all picture.

I didn't even know whether I should post this in hardware or software forum...that is how clueless I am.

Apart from telling me what one overclocks or underclocks, maybe what are the advantages and disadvantages.

A specific example with a particular note book would be great.

But once I get a basic intro I will go back and read the threads to get a more detailed picture...

TIA,

Justitia

[ikovac]

Hi Justitia,

I'll try to explain (I hope my english is good enough):

All digital electronic devices in a computer listen to certain beats, or clock. Every beat (clock) a processor can do something. Every time it does something, it uses some power and thus produces some heat (law of the nature to put it inshort). So if you take your CPU that is working at 2.0 GHz for example - then it can do 2x10 to the power of 9 (giga) operations in just one second. Now if you overclock - to let's say 2.1GHz it would do a bit more (more operations per second) - so it is faster, and a bit warmer. Now, it isn't just a processor that dances to the beat, there is memory too. It behaves similar to the processor (I mean listening to the beat), but just writes and reads data that processor needs. They are synchronized. That doesn't mean that they work at same frequency (or rate). They just cooperate, with more or less waiting for each other.

Now overclocking means pushing a clock to tick faster. Processor and memory can be overclocked. Pushing it to work faster produces more heat, and some other effects become visible too. It starts to make mistakes or errors. Those errors are already bad, but extra heat that is produced can damage it. It can burn out.

Advantages: Processor (CPU) or graphic processor (GPU) or memory (onboard or on graphic card) work faster thus making programs run faster. Games are also programs! Also manufacturers usually produce underclocked components - they don't want push it to the limit. In some way they are right, but again, it's free speed waiting in it.

Disadvantages: Heat (heatsink and fan aren't built for that), errors (for example artifacts - errors in overclocked rendering of a 3D/2D image), even burning the chip.

Underclocking - lowering the speed, slowing down the clock. Every component has factory setting for default frequency. This is going slower than that. Underclocking is important on notebooks. If you slow things down a bit - it uses less power per second and it produces less heat (cooler easily cools it).

Advantages: Less power per second, means more seconds - longer work. Less heat means less fan work - thus also preserving more battery and longer work. And to be honest in windows you don't need all that power or high speeds. That is why for example Pentium M processors have SpeedStep - technology that underclocks CPU if you don't use it - saving battery. Actually processors are most of the time on idle.

Disadvantages: Extreme underclocking can also produce errors and freezes. I have never heard that somebody lost his CPU or GPU because of that, but I can easily freeze my comp just by underclocking GPU for example.

Now i have like 10 years of experience in overclocking and have overclocked all my computers and notebooks, with at least 10 different graphic cards. I did push it to the limits, and never, NEVER killed any of the above mentioned. Notebooks are tricky - small and hot, but it can be done. Reward is very good.

So an example:
I bought my new notebook with 1.86 GHz Pentium M, processor, 2GB memory and Ati X700 128MB graphic card.
Already in BIOS there was setting that says "Advanced performance" or something. I enabled it and - it actually overclocks front side bus (link between processor and main memory) so both work 5% faster - giving me better results. So my Pentium M 1.86 GHz became 1.96 GHz. (memory also works faster, but you got the picture, I hope).
Now Ati x700 is a processor only for graphics. It is on a separate card and it has its own memory (dedicated). You can think of it as a small computer inside bigger computer. By using software tools like Notebook Hardware Control or Ati Tray Tools, or ATi Tool, I can overclock GPU and/or memory. Default GPU clock was 350MHz, Memory was at 300MHz (this is BTW underclocked for no known reason). So I actually have underclocked memory on my graphic card! So the procedure was in Ati tray tools:
1. Overclocked memory,
2. Overclocked GPU
3. Checked for artifacts
If there were no artifacts I went further, if there were some, I lowered speed and tried again
4. Benchmarked (this is for pure numbers only - to get the feeling how much I got)

So by repeating these steps I finally got that I can overclock to 400/400. That gave me around 25% faster games. Not bad. I also measured heat (you can find some graphs if you follow the links that Chaz gave you), and did some other things in order to get more stable combinations, but that is another story. (I'll just say that it can go even faster.)

I hope it helps,

Cheers,

[Justitia]

Ivan: That was not only exxtremely clear but poetic as well, that made the image of what was happening even clearer.


Chaz: I will be reading your thread next.

Thanks you guys, you just took me to the next level of computer comprehension

[BigV]

you've probably also heard of undervolting.

basically it sends less electricity to the CPU. part of overclocking involves sending adequate power to the CPU, as you increase the clock speed, you increase the voltage to maintain stability. however, manufacturers generally want to have maximum stability, so they send extra voltage to leave a margin of safety on their stock CPUs. You can use a program like notebook hardware control to reduce the amount of voltage used, then run a stress-test to ensure that there are no problems. I gained about a half-hour of battery time by doing this.

[ikovac]

Thanks, Justitia! I'm not a poet , but spent years in teaching computing to the people. Maybe I'm just skillful in explaining things. I guess it wasn't too bad.

Good point BigV! Now I'm interested, what processor do you have (hm... actually there it is in a signature ), and how much can you undervolt your CPU? What stress test do you use? Do you get any problems? I did it before, but never actually seen any battery gain. (Maybe I just forgot to check it? ). Thanks in advance.

So there must be and overvolting then. When you extremely overclock CPU and then you must raise voltage to maintain stability. But I think that is dangerous. I have never done it. Especially on a notebook. Can somebody confirm successful overvolting on a notebook?

Cheers,

[Justitia]

Originally Posted by ikovac

Thanks, Justitia! I'm not a poet , but spent years in teaching computing to the people. Maybe I'm just skillful in explaining things. I guess it wasn't too bad.
....Cheers,

Ikovac...I just noticed you're from Croatia.... I love Croatia. I was there a couple of years ago and spent a little over 2 weeks there, first in Dubrovnik, one of the most charming and fairytale like cities in the world and then driving up the Dalmation coast to Split. I spent time on Brach island... I wante dot buy a house there so bad.... The beaches are incredible all along the coast.. so azure blue and so clear you can see straight down to the ocen floor even in over 10 feet of water... Unbelievably beautiful and not spoiled yet by tourisnm. But that was a few years ago... I imagine the tourist industry must have grown... I didn't make it inland to Zagreb but I hear it is absolutely charming....
in

[ikovac]

Hi Justitia,

Yes you described it right. The uspoiled nature. The way we like it. It is a long way, but it is worth it.

My avatar pic is actually me at 5-6 m undersea on Vis island. I recommend Hvar, Vis and Korcula. If you ever go there, that is it. You will become our citizen. I promise. The sea there is unbelievable. 10 meters of crystal clear sea. In the evening, you can actually see the bottom like in some kind of an aquarium.

And because you are so kind and wrote that nice post I am sending you a small gift. A picture taken by me on Vis island, in a small "konoba" at the end of the world...

(And you have no mail set, and PM cannot have attachments, so I hope moderator will not kill me or anything).

Cheers,

[jivedaddy]

Ivan,

Hope you don't mind I downloaded the picture too? Looks great. I have a small (26 ft.) sailboat and bet the sailing there is awesome!

Thanks for the overclocking tutorial too! I have a new Acer Aspire 5672WLMi and sure would like some extra power. Are all video cards and processors cabable of being overclocked?

JD

[ikovac]

Hi jivedaddy,

That is nice. Pic is free of course. Enjoy. Actually Croatia is great place for sailing. Over thousand islands!

BTW I recommend you checking my signature links for more stuff on optimizing your comp. Heat, undervolting, underclocking etc...

Cheers,

[Charles P. Jefferies]

Ivan, thanks for putting all those great article links in your signature, very helpful indeed!