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Topic Title: Guide to Overclocking Your CPU
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Created On: 06/15/2004 09:59 PM
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 06/15/2004 09:59 PM
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parsifal
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Posts: 1460
Joined: 05/07/2004

***Overclocking WILL VOID warranty***

"How to overclock?" This is one of the most common questions in forums.AMD.com, so i've decided to get into the issue and the result was the following "guide".

Introduction
First off, overclock process depends on several factors such as Front Bus Frequency (FSB), Multipler, vCore voltage, RAM, Cooling System and Power Supply Unit (PSU), Motherboard and processor itself. FSB, multipler and vcore voltage are changed in BIOS so, why are the other factors important to overclock? That's because:
1. The user has to rise the vcore voltage to get high results and when the voltage is rised, the processor temperature also rises very fast and one good cooling system assures lower temps, therefore, the processor will more probably run stable and safe;
2. The user has to pump up FSB and if the RAM doesn't handles with the higher frequences the system will experience stability problems (freezing, BSODs, crashes), therefore it's wise to get good DDR RAM (400Mhz PC3200 if the motherboard supports it or 333Mhz PC2700, at least), the RAM brands are also very important, be sure you get a good brand, i.e. Kingston or Corsair;
3. Pumping up the voltages will demand more power from the PSU, the good cooling system fans (or the water cooling system pumps) also will, therfore be sure you get a good PSU [350W or more depending the hardware (PCI cards, DVD, USB devices, HD, fans) installed in your rig] from a good brand (i.e. Antec). As far as PSUs are concerned, brands are very important!
4. There are motherboards that are indeed more overclockable and i know i.e. nForce2 chipset is "friendly" than KT600 chipset, refer to Anandtech' ">http://anandtech.com/mb/showdoc.html?i=1842&p=12, hardOCP' ">http://hardocp.com/article.html?art=NTE2LDY= and FastLaneHW' ">http://www.fastlanehw.com/reviews.php?i=116&page=4 (thanks to SDA for the links)
5. The XP mobile processors have more overclockability than the rest of XP series but, even between same XP processor core and specs, the user will find that some are better than others to OC and some get hotter than others. Every processor is unique just like people.

Overclock "best settings"
Many people ask me" what are the best settings to overclock" their rigs. Well, that's not that simple. Every processor, every system is unique though having the same core, specs, RAM, hardware, etc. As they are different, their "reactions" to this or that overclock settings can (and will) be different. The user just has to find out the "best settings" by his own.

Unlocked and Superlocked Multiplers
What is this all about? Before 2003 week 39, all AMD XP series processors leaft factory with unlocked multipliers. This means the user could change it in BIOS and get awsome overclockings because the user not only could change FSB but also multiplier. After that moment, AMD started to lock the XP series multipliers at factory (except the XP mobiles), therfore the users can't change it in BIOS and so far, no "wire trick" or any other "trick" unlocked the multiplers, that's why it's called "superlocked". I don't know why AMD did that but i suppose they were aware of what was going on, i mean, why would one user buy the 3200+ XP if he could buy one cheeper and make it run at 3200+ speeds? If it was so, i can perfectly understand AMD's point of view and agree with it.

How to overclock in processors with superlocked multiplers
The user can't change multipiers but can overclock via FSB
At boot, when you hear the speaker beep or while the system is testing the memory press the "DEL" key to enter BIOS (some motherboards needs other keys to enter BIOS, refer to user's guide for details) once there, scroll the menu and enter "Advanced Chipset Features" or something like that, pump up the "System frequency" (FSB) about 10Mhz above the default setting (i.e. for FSB 266Mhz processors, 143Mhz; for FSB 333Mhz processors, 176Mhz and for FSB 400Mhz processors 210Mhz). To do so, you must set the "system performance" from "optimal" to "user define" or "expert" whatever you BIOS says; save and reboot.
If the system reboots, get into Windows and test the system with Prime95' ">http://mersenne.org/prime.htm for several hours (overnight is great)
If the system fails the test, pump up the voltage in small 0,05v steps, (if you are experience NO temperature problems) and test it always keeping an eye on temps.;
If at the time you reach the 1,85v setting, the system still fails the test, back down FSB.
If the system pass the test you can increase FSB in small 1 to 5Mhz steps and vcore voltage (if you're experience NO temperature problems), I insist that much in temperature because it's processor's enemy nº1.
Now, if the system doesn't reboot and the speacker becames to "talk", take it easy, all you have to do is to clean the CMOS. To do it, you must turn off PSU, take out the CMOS battery (looks like a niquel in motherboard), wait for 10secs and put it back, turn on PSU and reboot. In some mobos, it's needed to move the respective jumper or switch (refer to user's guide for details).
After rebooting you will probably get the message "default setup loaded" or something like that. Enter BIOS and set the FSB 2Mhz back the point were it crashed or, pump up the voltage only if you are experience NO temperature problems 1,85v is the "safe" voltage on air cooling systems.
In resume, that's it.

How to overclock in processors with unlocked multipliers
Well, the process is the same explained above except that user can change multipliers and get better results specially when combined with memory overclocking. When a CPU runs @ high FSBs synchronised with high rate RAMs (PC3200; PC3400) it takes full advantage of Memory frequencies so, FSB200Mhz x11=2200Mhz is better than FSB147 x15=2205Mhz.

Another BIOS settings that can be used to overclock
This settings are related with the memory, they are the memory frequency, memory timings and DDR voltage. I'll not explain this issue, but you can find it deeply explained in www.ocforum.com' ">http://www.ocforums.com/showthread.php?t=257741. In advance i can say that lower values means more performance but less overclockability and vice-versa; running the RAM "sync" with processor (FSBRAM ratio= 1:1) increases the stability and overall performance, "async" modes should be avoid in AMD XP systems.

Conclusion
Overclock is a easy process but must be donne with extreme caution and in small steps at a time. The user can't expect to obtain the same results others can, on the other hand, the user can expect more if his system's reactions to overclocking are better and stable, wich are always unpredictables. As you can see, it' s an "trial and error" processe and sometimes, a little luck helps... Just don't forget to test the system and to keep it at safe temperatures or you can do serious damages to it.

Other usefull links
http://www.hyperformance-pc.com/overclocking_faq.htm' ">http://www.hyperformance-pc.com/overclocking_faq.htm
Guide to System Thermal, Air Flow and Cooling explained' ">http://forums.amd.com/index.php?showtopic=11388
Power Supply Unit' ">http://forums.amd.com/index.php?showtopic=11246
Guide to Stability and Stress Testing' ">http://forums.amd.com/index.php?showtopic=12201
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