AMD Overclocking Guide

[BigMoose]

Introducing the New & Improved AMD Overclocking Guide which will take a look at not only the principles of overclocking an Athlon based system, but also this particular processor and the new obstacles that stand in the way of the perfect overclocking system.

Basic Terms of Overclocking

Chipset - A chipset is defined as “a group of microchips designed to work as a unit in performing one or more related functions.” As a general rule, today’s chipsets consist of two parts, a Northbridge and a Southbridge. Both of these terms will be discussed later, but the two working in tandem creates a better and more efficient flow of data with fewer conflicts. Common chipsets used with the Athlon XP processor at the time include the VIA KT400 as well as the nVidia nForce2. The nForce2 has emerged as a great chipset is the choice of overclockers.

Clock Multiplier - The Clock Multiplier is an internal setting of the processor that is used to determine the processor speed. As an example, if you have a processor that is set at the factory with a clock multiplier of 10 have a FSB of 100MHz, then the resulting processor speed is 1000MHz or 1GHz. It's a very simple and easy term but used frequently.

Double Data Rate (DDR) - Double Data Rate, or DDR as it is commonly called, is becoming very popular with the computer industry lately. DDR allows for the support of data transfers on both edges of each clock cycle (the rising and falling edges), effectively doubling the memory chip's data throughput. And even better is that all of the motherboards and the Athlon processors themselves support this feature. So not only can we double the effectiveness of our memory, but we can also double the speed at which data flows between areas of the motherboard too.

Front Side Bus (FSB) - In simple terms, the Front Side Bus (FSB) is the data path between the processor and the main memory. When used from an overclocker’s standpoint it is generally referred to as a speed measured in Megahertz (MHz). The higher the number, the faster the data flows.

Northbridge - The Northbridge is the portion of the chipset that communicates with the computer processor and controls interaction with memory, the Peripheral Component Interconnect (PCI) bus, Level 2 cache, and all Accelerated Graphics Port (AGP) activities. The Northbridge communicates with the processor using the Front Side Bus (FSB).

VAGP - VAGP refers to the voltage setting of the AGP port on the motherboard. Not all motherboards allow for the adjustment of this setting, but for those that do allow for it, the benefits can be great.

VCore - This is the voltage setting for the processor. This is where you can force your speeds to the next level, or completely fry your precious CPU.

VDIMM - This is where you set the voltage levels of your memory. Though higher voltages can help you achieve better overall speeds, they can also cause some system instabilities.

Basics of Overclocking

Now to the basics of overclocking and how it is done. You'll first boot up your computer and enter your BIOS. If your not sure how to do this go into the appropriate motherboard section and search there, it's usually the F2 button or something to that affect.

Once your into the BIOS you can now set your frequencies, voltages and timings. If you have bought a desktop chip and it is post-week 39 you will not be able to change the multiplier. If your not sure check out the steppings FAQ here: http://forums.extremeoverclocking.co...d.php?t=125129
But we must move onward, once you enter the screen in which you see the FSB, Multi, Voltages and Timings you'll know your at the right place. You'll want to start out with a low multiplier (such as 9 or 10) first to find your maximum FSB. First set your multi and then your FSB in 3-5mhz increments and then booting and testing your overclock stability by Prime95 and Memtest (see bottom for list of programs to download). Once you have hit a wall (computer freezes or testing shows your unstable) go back and raise the vcore to your CPU. Once you have found the absolute maximum FSB you can go back and start upping the multiplier in .5 increments. Same idea applies, once you fail, freeze or can't boot raise the vcore until you can. The maximum voltage you want to be running if you have aircooling is 1.95V (in Windows) and 2V with watercooling. If you have the balls you can venture to the about 2.1V for benchmarking but anything more than that will have a high risk of frying your CPU. Adding voltage to the northbridge and VAGP can also help in creating stability for your overclock. Also, a common overlook is the locking of the AGP/PCI frequnecy @ 66mhz. If you don't have a board that allows this it will hold back your overclock.

Now on to the question of RAM and your overclock. This is a key aspect as well and make or break a good overclock. Start out with getting some PC3200 RAM at the least with some decent timings, which are critical for AMD systems. When you first start out with your overclock set the vdimm to 2.8V and loosen the timings to 3-4-4-11 to make sure your RAM isn't hindering your overclock. Once you have found the highest FSB go back and start lowering your timings, as tighter timings result in faster speeds. The best possible timings are 2-2-2-5 but don't be worried if you can't achieve these. For some reason, the nForce2 chipset likes the final number in the RAM timings to be 11 instead of 7-10. If you hit a wall with your RAM, you can increase the voltage to 2.9V, which is the max most mobo's out have unless you plan on doing some voltage mods.

L12 Mod
This has been a hot topic for a while in the overclocking world and I will briefly try to explain it. Since the default fsb of the mobiles is 266, the 266->333/400, L12 mod WILL improve the max fsb on all boards with the nForce2 Ultra 400 chipset (Albatron KX18D Pro, DFI Ultra Infinity, Epox 8RDA, NF7 v2.0, Soltek SL-75FNR2-L, etc.) and possibly others. The most plausible explanation I have heard why this works is because connecting these bridges changes the latency timings between the front side bus and the cpu.

Suggested method:
http://www.geocities.com/trats102002/nf7sFsbsense.html
Alternate method:
http://www.xtremesystems.org/forums...&threadid=15300


Cooling and You

Cooling is a critical aspect of overclocking. As we increase the voltage, this generates more heat and heat creates instability in an overclock, and that is not what we want. Here is a list of general cooling solutions and what beats what: Air Cooling<Water Cooling<Phase Change<LN2. The general cooling overclockers use is air cooling, though some use water and phase change. If you want to have a high overclock you'll want to make sure you have good aircooling at the minimum as an overclocked CPU puts out alot of heat. A great setup would be a Thermalright SP97 with a 92MM Tornado.

Recommended Programs

• Prime95
• Memtest
• SiSoft Sandra 2004
• CPU-Z
• Motherboard Monitor 5

What to buy

If you're wondering what to buy for a new AthlonXP system look no farther! Here is what I would recommend:

CPU: XP-M 2400+ 35W
RAM: OCZ EB PC3700 or OCZ Platinum PC3200 Rev 2
Mobo: Abit NF7-S Rev 2
Cooling: Thermalright SP97/SLK947U with 92MM Tornado

If you have any questions, comments or suggestions please let me know. Thanks to Tweaktown and all the other members here who have contributed in one way or another!

Last Edited on 10/04/2004

[xeroxide]

Nice, also... for those with post week 39 cpu's (like myself)...
Its a good idea to *lock AGP slot at 66mhz* - found in the bios, this feature should increase stability and allow for a higher fsb overclock by making sure your extended cards (pci and agp) as well as hard-drives do not run faster than stock... this can cause data corruption and limit your overclock on the gfx card.

most common mobos with agp lock are the nforce 2s
not sure about others...

real nice, and neat. well thought out moose

[Sokur]

Very informative, if I wasnt already overclocked I would use it. I think you should add the L12 mod in there somewhere for an even higher FSB.

[Slif4ever]

yo, very nice guide... and as it said informative too.
|cheerz|

[YiZZo]

nice, imma start using it right now!

[stosh]

PRINTED and will use this tonight.

[Sokur]

Good to see you added that bit about the L12 mod. I think it's complete now. What about adding a HSF recommendation if your Mobo doesnt support the XP90 or SP97 (like mine) & they have to use a 3 prong clip HSF.

[BigMoose]

Thanks guys! Added more heatsink recommendations.

[Southpaw01]

thanks alot, motion for a sticky!

[davidhammock200]

When are you going to add the A64 info or did you already do that & put it somewhere else?

[Vic Romano]

Looks pretty good B-Moose. If i may make a suggestion, I think your vcore recommendations are a little screwy. 1.95vcore on air ? Most will never raise it that high. I would say you would be better recommending a max vcore as function of temperature. In that, raise your vcore as much as you can when you need too, but don't let your load temps get over, say 55°C, no matter what vcore you have. Maybe a llittle blurb about what kind of temps to expect and what you shouldn't exceed. Looks good..

[Jimmer411]

id remove the ocz eb 3700 reccomendation, as its no longer produced. looks good. a short explanation of ram timings and the terminology used would be helpful, as loosening and tightning of the timings and rheir effect on max overclock. i vote sticky as wel.

[The Punisher 64]

Hi, i've got a 2800+XP and Nforce 2 motherboard (Asus A7N8X-LA) and 512mb pc2700 ram and i was wondering how much i could overclock it to (I only have 1 intake fan and 1 exhaust)

[Fáté™]

Nice guide. Ive seen that or one very similar on quite a few sites ..

[SwampSnake]

asus A7N8X-E Deluxe
xp2800+ barton
coolermaster HAC-V81 HSF
2x256mb kingston hyperx dual channel pc3200
sapphire radeon 9600pro
hitachi deskstar 160gb 7200rpm
sb audigy {9400}
i have been recently considering overclocking my xp2800 to a xp3200 so i have been reading up on overclocking cos i wanna make sure i get this right .now i know i have to drop my multiplier down to 11 and up my cpu fsb to 200 mhz from its present 166mhz my question is about the memory at the moment my bios settings say
memory frequency {100%}
resulting frequency {166mhz}
memory timings {user defined}
latency times are 2.3.2.6T
Does this mean that when i change my cpu fsb to 200 mhz that the memory will automatically sync with the cpu or do i have to physically change the memory fsb to 200mhz,if so what do i set the memory frequency to, and as i shouldnt have to increase the vcore will there be any significant temp increase
thx in advance to anyone who can help

[Demi]

Thanks for the guide it helped alot. Im fairly new to overclocking, I used to have a 2500 Barton and all i did was crank up the bus, which now after reading the guide, I realize was just the tip of the iceburg. Im looking at building a new system, and really what to build it with overclocking in mind. As I've never done this before i was wondering if the choices Im looking at lend themselves to this purpose or not.
Socket 939 64 3200
Zalman CPU Cooler model CNPS700B-Cu LED
Crucial Ballistix 184-Pin 512MB DDR PC-3200 (another stick when i get the money)
Chaintech Nvidia NForce4 Ultra Model "vnf4/Ultra" Motherboard
also,
Is there a point where heat on the cpu gets high enough, before damaging, that it slows down the processor? Not like the max temp, but the optimum temp is a guess what im asking. If so what would that be on a 64 3200?
Thanks for the help.

[Demi]

Ive read the forum on the chaintek motherboard and from the sound of it the problems with it have for the most part have been resolved, but i dont know what alot of the posted problems mean. If there is a better suited motherboard for just a little more i would go with that but the price ranges really jump up on the sites ive been browsing.

[apekis]

about the multiplier on a7n8x m/b with xp2800+ (barton) .i can change the multi but it doesnt do nothing and if i save and exit bios, the system wont start.i have to press reset and set the multi at x12.5.it does the same even if i lower the cpu clock to 100mhz.any ideas?

[CompDude]

Your chip is probably locked.

[apekis]

i read a thread about that, but it wasnt clear enough, if you can try to set the multi or you cant change it at all when youre in bios.im going to try to see how can i unlock it.there have to be a way.thanks for your reply