Reasonable OC settings?

[rsbriggs]

I've got a 3.0 Ghz P4 in an Intel 865 board. Tried setting timings and such to "aggressive", and ended up having to clear the BIOS because the machine wouldn't boot anymore. Can anyone suggest a possible series of small, incremental changes that I could try making to the settings that might let me squeeze a bit more out of it?

Basically I know nothing about doing OC'ing, so saying something like "just set things to 405*12 and 2.5/2/2/2" is absolutely meaningless to me...

[MerePeer]

On one of my mobos the "Normal" vs. "Agressive" I think pertains to the cpu's interaction with memory. Although I have overclocked I have not changed from Normal. From a bit of searching it sounds like Aggressive will often result in instability and not very often result in better performance.

Here's my two cents and I've only begun this recently myself, so take with a grain of salt and hopefully other experts will chime in.
The most basic way to overclock is to increase the FSB. It is also one of the only ways on many modern chips because the other 'factor' in the total speed is the Multipler and those are usually 'locked' by the manufacturer so you cant change them. FSB times Multipler = speed. So taking my Sempron 2400 as an example. It is multipler locked at 10x ( chart here (http://www.thedigerati.us/info/amdcpuchart.html) ). It is supposed to be run at 166 (actually gets doubled to 333mhz) FSB. So 10x times 166 = 1660Mhz speed aka 1.6Ghz. So when I increased it to 190, then 190 X 10 = 1900 aka 1.9ghz. I have a motherboard which allows the FSB to be increased 1 mhz at a time, so I can gradually adjust it up or down. As it is adjusted higher and higher you will eventually hit problems. The first problem is instability: meaning it will partially boot then have a kernel fault, or it will boot all the way and then FAD or D2OL or DF or whatever you are running will die with some wierd errors you never saw before, or maybe the onboard video has lots of lines through it. Sometimes it will run for a day or two then decide to die -- maybe the heat got to it, maybe the power supply had a significant drop. Time to drop it down a mhz or two. Unfortunately there are too many factors and not enough diagnostics to pin all the problems down: maybe your memory doesnt like the faster speed, maybe the power supply isnt smooth, maybe you need to adjust your memory timings, maybe your onboard video doesnt like speeds above 166/333 mhz, on Intels maybe the AGP/PCI should not be raised-in-step with the FSB, and of course: not all chips are going to behave the same. So sometimes swapping in a different component can be helpful.
Another adjustment you can make is to bump up the "core voltage" a smidge. For the sempron it is supposed to get 1.60 and I havent gone beyond 1.675. This won't immediately make your system faster, what it does is give you more stability. Of course then I get greedy and want more speed -- vicious cycle I guess! There is some longer lasting danger with big increases in voltage but from what I've heard its ok to go up a little -- its not an issue of frying anything immediately, just some longterm (2 years :scratch: ) drift of the metal on the circuitboards with too much voltage in them I guess.
Yes, sometimes we bump things up so high the darn thing wont boot and you found the solution to that problem: a timeconsuming mobo reset and then reset all your favorite bios settings: and sometimes you have to hook back up the "power on" switch if you remove it like I do! But if you keep good track of what the last 'good' settings were (i.e. stable at 185, wont boot at 195, you can start to hone in on a reasonable settings. In the case of this sempron it seems happy at 194 (x 10 = 1.94ghz = FAD score 215 linux).
The memory speed is another bios setting and I like to keep "in step" with the CPU, meaning I change it from "default" to "100%". This assumes the memory has the extra speed available to match the FSB speeds you are setting, meaning: PC3200 can be used up to 200mhz fsb. If I was using PC2700 I would probably make sure the Percentage I used didnt go over 166 -- this might be accomplished also by using the "SPD" setting which I think uses a tiny bit of readonly-ID info on your memory stick to tell it what the memory timings (and speed?) are. Then there are those memory timings. I dont really understand them yet, but there are lots of places to read up on them (here's one I just found http://www6.tomshardware.com/howto/20010725/bios_tuning-04.html ) . Lately if I know my stick is 8-4-4-3 I will specifically set the BIOS that way (make sure you map the right number to the right field in the BIOS) until I have a stable O/C running -- maybe others will tell me this is wrong but I figured this would 'rule out' the memory as a factor during the FSB increases. After everything has settled a few days I might go back and see if I can drop it to 8-3-3-2.5 which I believe would result in faster memory access. Probably worth running some memtest -- like from the Knoppix cd.
In summary its small changes, monitor closely, repeat.

[room101]

I'm afraid you won't have much luck overclocking on a intel motherboard, i think they don't allow you to up the FSB by any more than 5%... You need a motherboard that uses a non intel chipset....

[rsbriggs]

Doesn't matter - didn't intend to overclock it anyways, really. I run my systems mostly straight - I want them stable 24x7 for years (my linux box at work, for example, has been up for 700+ days now). If I can fiddle and get maybe get 5% more out of it, I'd be more likely to buy an Asus or something next time around.

Have any suggestions for a MB that specifically caters to being OC'ed for Intel chips? I have a couple 2.66 Ghz processors laying around waiting for me to buy something to stick them in.... But, I tend to be more partial to buying two $59 boards and building two non-OC'ed boxen than spending $200 on a MB that might get me 20% more out of a particular CPU. (Guess I've never understood the advantages of building an OC system over building two non-OC'ed systems at the same speed, and for less money.)

[Evilmoose]

I personally like asus and abit boards for intel. I think you can clock a little higher with abit but asus is hard to beat for stability.
I have a 2.4c in an abit IS7 intel865 and have had it clocked up to 250FSB. If I could have kept it cool I would have left it there it was stable just too hot.
I used to be big into overclocking but now I tend to agree with you that 2 cheap systems are better for the money.