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» MEDIA (11) AMD Logo Bone Stock HTT Multiplier Being Set at 3x Finding the Max External Clock Frequency Bumping the RAM Voltage from 2.6V to 2.8V Making sure my hardware hasn\'t caught fire Overclocking Results 1 Overclocking Results 2 Overclocking Results Spreadsheet AMD Small

The Quick, Dirty and Painless Guide to Overclocking an AMD
by
Donald Bell

+•System Setup•+
Windows Vista Ultimate Edition x64
2x1GB Kingston HyperX PC3200 KHX3200AK2/2G, Timings 2-3-2-6-1T
Ati Radeon X1800XT w/Catalyst Drivers 7.8 @1600x1200
Sound Blaster X-Fi Platinum
Abit AT8 32X
Opteron 165 CCBWE
Western Digital Raptor WD740AD

+•Programs Used•+
Sisoft Sandra Lite XII
Super Pi
3DMark06
PCMark05
ORTHOS
CPUZ

My Mission: To bring new life to this old Opteron 165 socket 939 CPU!

Once considered the Holy Grail of computer geeks far and wide, overclocking continues to become more popular and rewarding with every advance in computer hardware. This guide is a no frills map to your prized destination of computer nirvana and self satisfaction.

There are three main entities which control your overclocking destiny; the CPU, memory, and motherboard. You can easily anger the beast within any of these components. When that happens, you will be greeted with the sound of your case fans and a black screen. But don’t panic, most motherboards with overclocking features have a BIOS cache in case of a failed overclocking attempt (just make sure you have it enabled). The BIOS cache will reset your settings to your previous successful POST (Power-On Self-Test). If you don’t have the luxury of cacheable BIOS, make sure you know where your CMOS reset jumper is located on your motherboard. If you have no idea, check your manual or your motherboard manufacturer’s webpage for more information.

Don’t forget, it is ALWAYS a good idea to see how others in the computer world have faired after having an adventure in overclock land. The knowledge of what to expect from your hardware is an invaluable tool that will potentially save lots of time. If you don't know where to look, FiringSquad's overclocking database is a great place to begin.

http://firingsquad.com/special/ocdb/

The first thing I like to do when overclocking is test the water before diving in. Eliminating variables is the key to a successful overclock when adjusting the processor, memory, and motherboard. The goal is to end up with one variable, free to be adjusted until the component has reached its maximum potential. Let’s start with the motherboard.

While your computer is POSTing, hit the key that opens the BIOS (Delete, F2, and F10 are common, typically your screen will announce what key takes you into “setup” (a.k.a. the BIOS). Once again, if you can't figure it out, consult your motherboard documentation. Upon entering the BIOS, you might need to explore a little to find the main areas that will require adjustment. For demonstration purposes, I’ll use an Abit AT8 32X as the motherboard of choice for this test.

Despite how strange it sounds, it is necessary to slow a few things down before we can start cranking things up. First the CPU Multiplier is lowered from 9x to 6x (the number doesn't really matter, just choose something that give enough headroom when overclocking the external clock) on the Opteron 165. This gives an effective speed of 1200MHz (6x200MHz). Next we’ll cut the RAM divider down to 266 from 400 on this pair of Kingston HyperX 2x1GB sticks (2-3-2-1T timings) for now. Many motherboards do not display the RAM dividers at its DDR speed. If your motherboard displays ram dividers at 66/100/133/166/200 Mhz, etc, make sure to keep that in mind whenever I reference dividers later on. However, you don’t need to worry about RAM timings yet, we will come back to that later.

Now, after adjusting both the CPU multiplier and the RAM divider to keep them out of the equation, you will need to cut the HTT multiplier (or LDT Bus as it’s called on this particular board) down to a level that will not exceed it normal operating frequency when you start to bump up the frequency on the external clock (you may have also heard this referred to as the Front Side Bus, FSB, etc). The external clock’s stock speed is 200MHz while the HTT multiplier's stock setting is 5x (5 times the external clock equaling 1000MHz). It’s typically a safe bet to set the multiplier to 2x or 3x (400MHz and 600MHz as seen on this Abit motherboard). Now that all the settings are in place, it’s time to shift gears and speed things up. Let the overclocking begin!

After all those adjustments, it would probably be a good idea to hit F10, save those settings and reboot. Head back into the BIOS and pick things up from the external clock frequency adjustment. As mentioned before, a little research can tell you quite a lot about a particular setup and its overclocking potential. I found that other overclockers on a few major forums said that Abit AT8 32X motherboards will generally hit a 300MHz external clock pretty easily. So, I’ll bump the frequency up from 200MHz to 250MHz, cross my fingers, reboot, and see what happens. Now that I’ve successfully rebooted, I’m going to raise the frequency in increments of 5MHz. After every adjustment, repeat the reboot process just like the first adjustment. When it finally comes to the point where the motherboard can no longer POST, follow the instructions in the second paragraph to get back to the BIOS. We have just found the maximum external clock frequency. In this case its 320MHz. Write it down!

Before moving on to the RAM, the external clock will need to be reset back to 200MHz. Set the RAM divider back to 400 and be sure your timings are set to the stock advertised settings (2-3-2-6-1T). Save, reboot, then find the RAM’s ceiling by slowly bumping up the external clock a few MHz at a time, just the like before. After finding the max, boot into windows and fire up an error testing program that can verify that the RAM is stable. ORTHOS is probably one of the simplest programs to use to test RAM and CPU stability. If RAM is severely unstable, Windows will either throw a BSOD or a rounding error in ORTHOS. In many situations, increasing the RAM voltage by a small amount can help secure that desired overclock. I don’t recommend increasing the voltage any more than .2V for beginners. As always though, when overclocking and increasing voltages, remember that there is always a risk of damaging hardware if you push too far. I was surprised to find that my PC3200 sticks were able to achieve an overclock of DDR450 on the stock timings at the stock voltage. With this much headroom on the RAM, it will be easier later to sync the overclocks of the motherboard, cpu and memory.

Now we move on to the big papa, the Opteron 165. With all of the previous testing reset back to the “low speed” configuration (just set the RAM divider back to 266), set the CPU multiplier back to the max (in this case 9x). Once again, bump up the external clock speed, starting at 200MHz in small increments until finding the max POSTable clock speed. Typically the max POSTable clock speed will not boot into Windows so it will need to be knocked down a notch. If you find yourself running into a brick wall, try bumping the CPU voltage by 0.05V or 0.1V. Once again, there are risks with increasing voltage on a CPU, the first and foremost is heat. Throughout the entire process it is crucial to monitor your CPU temps ensuring they are not spiking to dangerous levels. Also, beware your load temps when testing stability in ORTHOS.

There is a good rule of thumb I like to go by when finding a CPU’s maximum potential: “Max POST Speed x 0.95 = Start Stability Test”. 95% of your max POSTable speed is typically a good place to start when testing for stability. CPU stability testing in ORTHOS should go for 24 hours or more without errors to be considered stable. This “Opty” recorded a max stable overclock of 2.44GHz, 640MHz above stock even after 30 hours of ORTHOS abuse!

Make sure you check out the graphs for some hardcore numbers showing how much of an effect a simple CPU overclock can have!


Last but most certainly not least, we will assemble the pieces of the puzzle. Here is what we know:
Max Stable CPU: 9x271MHz = 2439MHz
Max Stable Ram: DDR450 @ 2-3-2-6-1T
Max Stable External Clock = 320MHz

Now we must remember what is most important and what gives the most performance benefit. The CPU and RAM are where the real gains will show. As far as the HTT multiplier in relation to the external clock goes, just keep the result between 600 and 1000 (i.e. an external clock of 271 times 3x HTT = 813MHz). The performance difference is pretty much negligible in that range. Luckily, in this particular case, we didn’t have to compromise between the RAM and CPU. If we keep the CPU settings as is, we will achieve DDR450 with a 333 divider.

Now if you run into an issue with the divider being just a little too high for your RAM, try loosening your timings a bit. For instance, if I had a FSB of 285MHz on a 333 divider, I would loosen my RAM timings to 2.5-4-4-8 to achieve DDR475 instead of dropping down to a 266 divider and having to use my ram at DDR380

Please remember that this is only a guide. Overclocking will disqualify most hardware from their original warranties. Neither myself, FiringSquad, nor AMD will be responsible for any damages or problems that may arise from referencing this guide. Please beware and only use this guide if you are willing assume any risk involved in the overclocking process.

This was an original entry by Donald Bell