Explain to me overclocking and underclocking....

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

 

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,

 

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

 

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.

 

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,

 

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

 

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,

 

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

 

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,

 

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

 

Thanks Chaz,

I hope that will help the people to quickly get at least some info, and then we can discuss it. I hope it helps. And this gamebooks forum is still young and has the good info more condensed if you know what I mean.

Cheers,

 

Oooooo, ikovac that's you eh? I thought you just got it off some National Geographic site or something hahahaha.

Cooooooooool, so you're not just a nerd like the rest of us here.

Great information, you know your stuff. You've made experts out of all the new people.

Cheers,
Mike

 

Hi Mike,

Nerd sounds a bit too harsh. Let's say advanced user - who likes nice beaches, dives, has a beautiful girl and drinks beer. A lot. Computer is no more than a tool for me. Great tool. My preciousssss tool. I also like helping people if I can.

Cheers,

 

Hehe I agree with Ivan,

I wont call myself a nerd, because I am **** good looking But yes, I do love games and to tweak... computers are a good way to have some fun.

Charlie-Peru

EDIT: Thanks Ivan for your downclock thread! I have downclocked my CPU and GPU now a little bit and I can really see, hear and feel the difference! If I would go further (which is easily possible) I could get a cool machine!
Here is a 3dmark05 score to show the difference:

Overclock: Full 1.73 GHz, GPU: 372:330, every setting optimalized (wireless off and such things): 2605

Downclock: 1.73 Ghz running on 0,1V lower, GPU: 282:237, wireles on: 1905

Stock: Full 1.73 Ghz, GPU: 351:297, wireless off: 2280.

My laptop runs cool now without any performance loss in Word, surfing and such things. In game it is very different, the downclock of the GPU lower the fps a lot!

 

Hey Charlie!

Great man! I am glad that my posts helped you to get the general idea.

In total - my default settings were 2280 3dmark05 at 85 C and now I get 3000 3dmark05 at 72 degrees C. That sounds much better to me.

Underclocking the GPU is for WIndows work only. Beware: below 100/100 you will most probably experience issues (lockups, resets) in video play.

Cheers,

Ivan

 

Thanks Ivan!

Its incredible that you get a higher score while having a lower temperature... I am also planning to buy cooling paste for my CPU and GPU. I read it on the forum of gamebooks.com. Can you post some pictures of how to add cooling paste, because all I can find of our desktops...

Thanks,

Charlie-Peru

 

Hi Charlie,

Check my sig for some interesting pictures of the interior of my notebook. BTW I haven't add any thermal paste to my system. All is by default.

BUT - I disassembled my notebook already many times - it is even easier to apply the thermal paste on my system than on some desktops. All I need is to unscrew 14 screws and apply paste on GPU and CPU. Not tricky at all.

Cheers,

Ivan

 

since we're talking about cooling our laptops (or in my case, my future laptop ) is it possible to undervolt the GPU? or is that not advisable?

 

I have never tried nor I have any knowledge of it. Also there is no tool for such a thing. But it must be possible somehow I guess.

Ivan

 

oh ok, thanks ikovac

btw, your articles were very helpful! i know what i'm doing once i get my laptop...heheh

 

Cheers, yin!

I'll be glad to help if you have any questions and I know the answer.

Ivan

 

nice! i'll keep that in mind. i'll most likely get my laptop in late august, so i'll give you a shout around then if i run into complications. thanks in advance

 

overclocking laptop is very limited i would sucrifice couple of mhz of overclocking just to keep my laptop away from heat never will o/c my laptop, maybe if i get a desktop with AMD Athlon 64 X2 4800+ and DFI LANPartyUT NF4 SLI-DR Expert then i will do it with a big smile on my face !!

 

OC + undervolting can help a bit in that case - In fact my notebook is 20% faster in games (GPU and CPU OC), and 10 degrees C cooler than the default settings. Speed for nothing.

Cheers,

Ivan

 

Ikovac, if o/c will decrease the temp by 10c everybody would o/c no one will go and by coolers etc... Or am I mistaken?
Plus how could u increase the FSB with no need to increase the voltage?
How much overclock you doing? Is it 300+MHz or 30 MHz
Enlighten me please.

 

Hi 31337,

No. Undervolting and coolers make Notebooks run cool.

OC FSB makes CPU run hotter. Take this example: OC FSB by 5% is making 133 MHZ bus to run at 140 MHz. That means that memory also runs at 140x4 MHz externally, and CPU runs for example at 16x140 internally - meaning that in my case PentiumM750 1,86 GHz actually runs at 1,96 GHz. Not much eh?Now memory at 140 MHz quadpumped + faster FSB + faster CPU (at 1,96 GHz) are FASTER than 133 quadpumped + 133 MHz FSB + 2,0 GHz Pentium M. Temp rises only 3 degrees C! The CPU at this small speed incerase needs no overvolting to make it stable. On the contrary... read on.

OC GPU - my x700 runs at 350/300 and hits around 80 degrees C in games scoring 2300 3dmark05. If I overclock it to 410/430 and set latencies to optimal values it can easily hit 3000 or more 3dmark05 at 84 degrees C!

Now as you already know - CPU multipliers can change every 1/2000 of the second depending on the CPU load. It is called Speedstep. Every step runs at particular voltage. By using tools like NHC you can lower them. For example, 16x multiplier is supposed to run at 1,3 V. If I measure the temperature at 100% load it hits 78 degrees C. If I lower the voltage down to 1,1V - it will never hit 70! Speed is not affected. If you lower it too much it will affect the stability. That is why you must raise voltage in order to get it stable again.

So a small OC of the CPU makes it run considerably faster. Small undervolting makes it considerably cooler even if the CPU is overclocked. OC GPU makes gaming 20-25% faster. In total you get the numbers I gave.

Try my sig links, there are also some nice graphs that can explain this stuff.

Cheers,

Ivan

 

Thanks ikovac for you're the explaining you've done
I had once water cooled rig with P4 3 GHz LGA 775 and Gigabyte 3D AURORA Super Aluminum Mid Tower - Water-cooled Edition. Running at around 4215 MHz it gets bumpy bit so I had to go down to 4050 MHz
But then I stopped all this I even don't want to use any desktop again... Laptops are fancier and less cords less noise.

 

I share your opinion about laptops. And your overclocking is absolutely an overkill for a notebook. I like the idea and I am glad you did it. That means that you knew what you were doing. Great numbers. I also think that notebook is much harder to overclock and be stable.


Cheers,

Ivan

 

that was in early july. i got my laptop now, the F3Jm, and i'm running 2 instances of Prinme95 (one for each processor, i needed to run one normally and the other with command -A1). at stock voltage the T2400 is 66C at max load (i only ran the two prime95 for like 20min). ambient temperature of my room is currently 24C ish. undervolting from 1.2625V (stock) to 1.0375V lowers the CPU temp to around 58C!

on another note, i watched these temps using NHC2.0. while keeping the prime95 running, i lowered the voltage to see how fast the temp would drop. WITHIN 3 SECONDS it went from 66C to 58C!! then it goes down to 56C within a minute and pretty much stays there. the fan does seem to be running at a higher speed at 66C, so with a sudden decrease in heat output i'm guessing the high air flow took away the heat immediately.

yup, this is first hand experience that shows undervolting is very beneficial.
yin

p.s. there is a lower limit of 0.9500V on the Centrino Duo.
p.s.s. does anyone know how to undervolt a GPU? or is that not possible?

 

Dammit! You beat me to it... By about 8 months...

 

that was a great explanation i was wondering the same thing, im very new at laptops, and computers overall. thanks

 

Hi guys,

I got back from a looong vacation (40 days at the seaside!) Snorkeling, taking underwater pics and so on...

Yin - yup - that is what I was talking about. Although this thread is for overclocking mainly, I can tell you that undervolting the GPU is so far impossible, as far as i know.

jalf - well, you can still improve it....

j stein - don't worry - stick to this forum, it is a great place of good info...

Cheers,

Ivan