AMD64 overclocking guide

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AMD64 overclocking guide

Postby Peanya » Sun Nov 28, 2004 9:53 pm

Please keep in mind that there never is any guarantee of an overclock, and all overclocking is done at your own risk! If you push something way too far, damage can be done.

To overclock the AMD64, we need to make sure of a few things before we try anything. First, you need a very good power supply. You’ll need a quality name brand and it should have at least 22 amps on the +12V rail or more. A cheap power supply WILL limit overclocking considerably. Secondly, you need quality memory. Two year-old PC4000 memory won’t cut it! Because the memory controller is built into the processor, many people assume that issues are strictly with the board. This just isn’t true. There are newer types of memory made today that are designed to maximize the performance of the AMD64’s on-die memory controller. Specifically: Micron’s new chips used in OCZ’s EB series (which is discontinued) and Crucial’s Ballistix line. Other excellent memory is memory based on Samsung’s new TCCD PC4000 chips. You’ll usually see this labeled as PC3200 with 2-2-2-5 timings. Third, we need good cooling to make sure we’re not overheating the CPU. Many have reported excellent overclocks with the stock cooler, but as always, watch your temps! Finally, we need a board that will overclock! Some boards don’t have working AGP & PCI locks; so overclocking these is extremely limited. This guide is going on the assumption you have an Nforce or VIA chipset with working locks. All that being said, let’s get started!

This is based on the assumption that you’ve overclocked older CPU’s in the past. There is one big change with the AMD64, and that’s the LT bus (AMD’s name for Hypertransport, also called LDT for Lightning Data Transport). With an older system you’d simply up the FSB until you lost stability, then boost your voltages of either the CPU and/or memory. You might also relax the timings. To overclock successfully, we need to do a lot more than just that, and also do a lot of trial and error. I’m writing this with a goal of 250MHz on the memory (DDR500). If you want to go farther, it’s up to you.
The first thing to do is lower the memory ratio and CPU ratio. A multiplier of 8 on the CPU will do, and set the memory to the 333MHz speed. Some boards will have a ratio of 6:5 instead. Next, we’ll raise the LT bus multiplier to 4 instead of 5, and set the base frequency to 250MHz, while leaving everything else at stock voltages. Now check for stability. A good test would be to use multiple apps that take advantage of the video bus and your disk drives. I tested using EQ while defragging. SANDRA also has tests which can help here. If you want to be able to push your memory further (not yet, but after we’ve tested the LT bus) then you can reduce the LT multiplier to 3, lower the memory ratio another notch, and set the CPU multiplier lower again. Now you can check the frequency all the way to 333MHz. What we’re doing here is testing to make sure there’s no weakness in the LT bus, and if it will overclock well. Going past 300MHz won’t benefit, as no current memory will overclock that far. If you’ve lost stability with either the 4 or 3 multiplier, try reducing the speed a little or give a very small bump up to the LT and Northbridge voltage.
Once we’ve determined the max LT frequency, if any, now we can move to the memory. Set the LT freq back to stock, and leave the multiplier to 4. We’re still not overclocking the CPU just yet; so leave that multiplier at 8. From here, set the memory back to DDR400 or 1:1. Assuming the LT was stable to 250MHz, we’re now going to overclock the memory. Overclock it just like you would any system: raising the voltage and/or relaxing the timings as necessary. Of course, always check the stability of the system. Good overclocks are stable. Now I’ve seen reports of the AMD64 showing no errors in Memtest, and stable in gaming, but Prime95 crashes. I don’t know if this is related to the BIOS, the CPU driver, or just small enough errors that only prime catches it, but if you experience this, you still might have a stable system.
So far so good? Great! Let’s get to the final part, the CPU. Now we can set the multiplier back to normal, now that we know the limits of the memory and LT bus. Let’s assume that both are stable at 250MHz. We can simply reset the CPU multiplier back to stock and slowly raise the LT speed until we lose stability. Then we will know it’s time to raise the voltage. It seems that the AMD64 can be over volted easier than many other CPU’s. Then again, this might be to me using a 90nm CPU vs. a 130nm.
This will probably leave a few questions open to the beginner overclocker, but this is a very brief guide for the experienced. Basically the biggest question will probably be the LT bus. This is the bus that connects to the AGP,PCI, IDE, and almost everything else in the system. Only the memory is on a separate bus. Overclocking it past 1GHz can result in a loss of stability, so that’s why we have the multipliers.
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Postby Davek804 » Tue Nov 30, 2004 8:25 am

Deserving of a sticky once you figure out tht current lock or w/e you said.
"We must embrace pain and burn it as fuel for our journey."
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Postby snap355 » Tue Nov 30, 2004 9:37 am

Good start for peeps like me
[url=http://www.motherboards.org/folding/index.html] Lend a hand and help with the folding project. Come join our 33258 team!

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Postby Peanya » Thu Dec 02, 2004 8:21 pm

From the BIOs. Although you can up the LT bus speed and the voltages from Windows.
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Re: AMD64 overclocking guide

Postby frankergin » Wed Dec 29, 2004 7:14 am

This is a very useful guide to those new to A64 OCing like me. I have overclocked a few AMD cpu's (K7s) already but this A64 thingy is really a bit of a head scratcher. I have been reading a lot of guides online about OCing A64 and all these divider / ratio and HT / LDT stuff can get annoying at times. Im still practically fumbling my way through. I recently bought an Abit AV8 with a 3200+ Winchester and I want to get started OCing and so far this guide of yours has been the easier one for me to settle with. However there are a few things I'd like to clarify if you bear with me:
Peanya wrote: I’m writing this with a goal of 250MHz on the memory (DDR500). If you want to go farther, it’s up to you.
The first thing to do is lower the memory ratio and CPU ratio. A multiplier of 8 on the CPU will do, and set the memory to the 333MHz speed. Some boards will have a ratio of 6:5 instead. Next, we’ll raise the LT bus multiplier to 4 instead of 5, and set the base frequency to 250MHz, while leaving everything else at stock voltages. Now check for stability. A good test would be to use multiple apps that take advantage of the video bus and your disk drives. I tested using EQ while defragging. SANDRA also has tests which can help here. If you want to be able to push your memory further (not yet, but after we’ve tested the LT bus) then you can reduce the LT multiplier to 3, lower the memory ratio another notch, and set the CPU multiplier lower again. Now you can check the frequency all the way to 333MHz. What we’re doing here is testing to make sure there’s no weakness in the LT bus, and if it will overclock well. Going past 300MHz won’t benefit, as no current memory will overclock that far. If you’ve lost stability with either the 4 or 3 multiplier, try reducing the speed a little or give a very small bump up to the LT and Northbridge voltage.

I'd like to correlate this with what actually needs to be done in the bios and please confirm if I'm right. I am using bios 1.7 by the way.

Go to OC Guru:

1.) CPU Operating Speed - Change to -> 'User Define'
2.) External Clock - Key in 250Mhz <--Is this what you refer to as base frequency above? Is this how we OC the memory?
3.) Multiplier Factor - Lower down to 9 or 8
4.) AGP Ratio - 'Fixed'

Then Go to Advanced Chipset Features

1.) Choose LDT & PCI Bus Control - Lower multi from 5x to 4x
2.) Go back to DRAM Configuration - Under DRAM Timing Selectable choose 'Manual'
3.) Under DRAM Clock - This is where you select divider (eg 6:5 or DDR 333)
One thing I noticed in the bios under DRAM configuration, is that these two options that say 'Current FSB Frequency' and 'Current DRAM Frequency' always stay constant and fixed. I thought these change when you change the frequency and DRAM Clock? See? I'm terribly confused about this. Anyway, once we determine that the example above of 250Mhz is stable enough, we change it slowly all the way up to 333 to make it 1:1 with the FSB? Am I getting that right?
Peanya wrote:Once we’ve determined the max LT frequency, if any, now we can move to the memory. Set the LT freq back to stock, and leave the multiplier to 4. We’re still not overclocking the CPU just yet; so leave that multiplier at 8. From here, set the memory back to DDR400 or 1:1. Assuming the LT was stable to 250MHz, we’re now going to overclock the memory. Overclock it just like you would any system: raising the voltage and/or relaxing the timings as necessary. Of course, always check the stability of the system.

Where is this done? OCing the memory? Back to 'External Clock' in OC Guru? Where you change to 'User Define' and key in the mhz/freq? Is that right? Of course the voltage setting is obvious.

Peanya wrote:So far so good? Great! Let’s get to the final part, the CPU. Now we can set the multiplier back to normal, now that we know the limits of the memory and LT bus. Let’s assume that both are stable at 250MHz. We can simply reset the CPU multiplier back to stock and slowly raise the LT speed until we lose stability. Then we will know it’s time to raise the voltage. It seems that the AMD64 can be over volted easier than many other CPU’s. Then again, this might be to me using a 90nm CPU vs. a 130nm.
This will probably leave a few questions open to the beginner overclocker, but this is a very brief guide for the experienced. Basically the biggest question will probably be the LT bus. This is the bus that connects to the AGP,PCI, IDE, and almost everything else in the system. Only the memory is on a separate bus. Overclocking it past 1GHz can result in a loss of stability, so that’s why we have the multipliers.

This part about OCing the CPU is easier to grasp. Just leave the multi on to its default or highest setting its locked upwards on A64s. Thanks for any clarification about my queries and kudos to your guide.
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Postby king_billy » Sun Mar 20, 2005 3:17 am

noob here,is this guide the same for socket 754 on abit kv8 pro. :oops: :oops:
abit kv8-pro
amd athlon64 3000+(754)
1gb corsairvs pc3200
western digital 36g raptor
200g samsung
20g maxtor
crucial 9800pro
16x dual layer +/-dvdrw
NU-16xdvd/52xcdrw combi
thermaltake x-blower
zalman cnps7000b-cu ultra quiet
hiper typeR 480w
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Postby Sabrewings » Sun Mar 20, 2005 11:59 am

king_billy wrote:noob here,is this guide the same for socket 754 on abit kv8 pro. :oops: :oops:


Yep, it'll work for both.
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Postby king_billy » Sun Mar 20, 2005 11:25 pm

thanks,sabre will have a read over this guide and take as much onboard as i can,thanks :D
abit kv8-pro
amd athlon64 3000+(754)
1gb corsairvs pc3200
western digital 36g raptor
200g samsung
20g maxtor
crucial 9800pro
16x dual layer +/-dvdrw
NU-16xdvd/52xcdrw combi
thermaltake x-blower
zalman cnps7000b-cu ultra quiet
hiper typeR 480w
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Postby galvanocentric » Mon May 16, 2005 6:21 pm

Maybe this'll finally solve my puzzlin' dillema of how the devil to get my processor past 220Mhz on the FSB. Danke.
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