I once overclocked an Intel in a nightmare and it was HORRIBLE Senior
 OCF's Plaything
Join Date: Mar 2008
Location: St. Louis MO
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Overclocking the Phenom II
Overclocking the Phenom II
Overclocking the Phenom II is a simply complicated task. What I mean is that you will be able to overclock right from the start with no problems, but as you go higher in clock speeds things become more difficult.
In this first section, I will be talking primarly about how to generall overclock your Phenom II. In the other sections I will be talking more indepth about the Phenom II and how it behaves. There is also a section about how to overclock the Phenom II Thuban, but it is more about the new tricks it has compared to the old Deneb CPU.
Note: Please be familiar with your motherboard BIOS. All settings that I talk about will be located in your motherboard BIOS. Each motherboard is different and you should learn what each setting is before beginning to overclock.
System Setup
Alright so before all of this information hits you, here is the hardware I used.- Phenom II 940 Stepping 2
- Asus M3A79T-Deluxe Bios Version 0602
- OCZ Reaper 1066 Cas 5 4gigs (2x2gig sticks)
- MSI 8600GTS
- 1TB (multi-partitioned) SATA HDD
- Rocketfish 700w Power supply
- Antec 900 with 3 120mm fans and 1 250mm fan
- Cooling:
- Stock AMD heatsink + fan + thermal paste (if stated)
- Swiftech H20-220-APEX-GT CPU Liquid Cooling Kit
- Windows 7 64-bit, Windows Vista 64-bit, Windows XP 32-bit (if stated)
Overlocking with the Phenom II
In this section I will finally teach you how to overclock the Phenom II. In general, the Phenom II is typically an easy processor to overclock. In no time, you should be able to go from 0% - 29% using your stock cooler and thermal paste. But going above and beyond, things will start to become more complicated. Things become even more complicated as you try to factor in a higher benchmark scores with your benchmarks.
For the rest of this section I will talk about each individual part that you will need to overclock. For beginners, I suggest that you read everything before acting. It will allow you to understand how things work.
Memory
First thing is the basics of RAM. Your RAM has a direct link to your CPU; there is no chip in between. This means that the CPU has an IMC (Integrated Memory Controller). There are two parts to the RAM : DRAM Frequency, and RAM Timings.
DRAM Frequency
The DRAM Frequency is the speed of your RAM. For the Phenom II there are four different basic frequencies. They are: 400, 667, 800, and 1066. Each of these speeds has a ratio. These ratios are what determine the speed of your RAM. The ratio is the FSB (Front Side Bus) and the DRAM Frequency [Seen as FSB : DRAM] . Table 1 should help explain everything. The DRAM Frequency can be changed based on the FSB. Using one of the ratios and a simple equation, you can determine the speed of which your RAM is running.

DRAM Frequency = [ (FSB * DRAM Ratio) / FSB Ratio ] * 2
For example I will calculate 1066 RAM: (Using standard AMD Settings)
200 * 8 = 1600
1600 / 3 = 533.333
533.33 * 2 = 1066.666
Now let’s say you have a 266 FSB. Still using 1066 RAM Ratio we would get these new results:
266 * 8 = 2128
2128 / 3 = 709.333
709.333 * 2 = 1418.667
You now have some really fast RAM, in fact this is most likely not possible for most RAM. But now you get the general idea. The FSB of your CPU will determine the speed of your RAM. By using the equation from above you will be able to calculate your RAM speed. This will serve as a very useful tool as you overclock your Phenom II.
NOTE: When configuring the ratio of your RAM, not all BIOS’s will not be the same. Each motherboard maker has their own way of making their BIOS. Please consult your motherboard manual to determine how to configure your RAM ratio.
The RAM ratio will be shown in one of two ways depending on your motherboard maker. First way is the basic ratio, just like my table from above. The menu will allow you to choose the ratio you want. The second way will be the showing of the four basic DRAM Frequencies. They will go in order 400, 667, 800, and 1066. These numbers represent the ratio you want.
RAM Timings
Now that you know how to determine the speed of your RAM, you can now set the Timings of your RAM. Depending on your motherboard maker, you will be able to fine tune your RAM timings. Your RAM timings represent the number of cycles it takes for information to be processed. There are several different types of timings you can modify but there are only six that you will want to work with. I would suggest that you do not touch the others unless you know what they do.
The six timings that you will tweak are: Cas Latency (CL), RAS# to CAS# Delay (tRCD), RAS# Precharge (tRP), Cycle Time (tRAS), Bank Cycle Time (tRC), and Command Rate (CR). These timings are directly affected by the speed of your RAM. Depending on your RAM manufacture there are a couple basic timings that you will most defiantly use while overclocking the Phenom II. Each timing works with a corresponding DRAM Frequency. NOTE: Please consult your RAM manual to find your RAM timings, my list is considered a default for each speed, but your RAM could be different.

The timings are most commonly represented as CL-tRCD-tRP-tRAS. For example: 5-5-5-15. For now, the default timings of your RAM should prove to be the best for overclocking in the 3.0 GHz range.
In some cases you will have to change the RAM timings to something unusual. In most cases it creates a more stable environment. I have found that using a 5-7-7-27-32 1066 Ram Setting in a 64bit environment is more stable than a 5-5-5-15 1066 or 800 Ram Setting.
CPU
The Phenom II is separated into two parts: Part 1 is the cores of the CPU. Part 2 is the NB, and HTT. In fact the Second part of the CPU is actually just the CPU-NB. The HTT and a couple other things are what make up the CPU-NB but to make things easy on you, I will talk as if the CPU-NB and the HTT are two different entities. (Which they are in reality but in hardware not so much, but then again are one in the same. Confusing isn’t it…)
For the first part of the CPU, you have the cores. The cores are connected by the FSB or HT Link (HTL), even the CPU-NB runs on it. The FSB always has a stock frequency of 200 MHz. The core is then multiplied by the CPU Multiplier to create the actual speed of the core. This is also applied to the CPU-NB, and HTT.
In order to overclock your computer, most people would simply increase the FSB. In 90% of all cases this is true, the other 10% of people have something called a BE or Black Edition CPU. These CPUs have an unlocked multiplier and will allow the user to just increase the multiplier of the cores thus increasing the speed of the CPU. So let us look at how the FSB and Multiplier can be used to overclock the CPU. For my first example I will use the Phenom II 810. This CPU has a stock speed of 2.8 GHz.
Stock: 200 * 14 = 2800 MHz
In other terms
FSB * CPU Multiplier = Speed of CPU
With the 810, I can only increase the FSB in order to overclock the CPU itself. So for this next example I will increase the FSB to create a 3000 MHz CPU or a 3.0 GHz core speed.
OC: 215 * 14 ≈ 3000 MHz
You roughly have a 3.0 GHz CPU now, in fact it is a tad bit faster, but that is ok.
For this next example I will take a Phenom II 940 BE CPU and overclock it. Remember the BE CPUs have an unlocked multiplier so you will not have to increase the FSB to get a higher clocked CPU. There are many benefits to this and they will be discussed in detail later in this section.
OC: 200 * 15 ≈ 3000 MHz
With just using the CPU – Multiplier I was able to up the CPU speed to a clock speed of 3000 MHz or 3.0 GHz.
One question that is probably in your mind is: Is there a difference between increasing the FSB rather than the Multiplier and vice versa? In truth no. If you have a BE CPU, there is no difference other then what will be talked about later in this section. But for a CPU that has a core speed of 2.8 GHz that and is increased to 3.0 GHz either technique will not create a faster CPU if you increased the FSB or the Multiplier or both. Just know that the FSB will affect other things then the CPU core speed.
Now that you understand how to overclock your CPU. Let us look at the second part of the CPU. The second part contains the CPU-NB, and HTT. In here everything is still connected by the FSB of the CPU, and each part has its own speed. So, the CPU-NB and HTT have their own speeds, and they work the same way as the CPU cores. Simply put, they both have their own multiplier and they go off the FSB. For example let us look at the 810 once more at stock speeds.
Stock:
200 * 14 = 2800 MHz Core Speed
200 * 9 = 1800 MHz CPU-NB Speed
200 * 9 = 1800 MHz HTT Speed
As you can see its just as simple as the CPU core speed calculation. One thing you should notice right away is that the CPU-NB and the HTT are using the same multipliers at stock settings. Remember they have their own separate multiplier but they do in fact run at the same speeds at stock. One thing to note and always remember is that the HTT can never go higher than the CPU-NB speed. The speed of your CPU-NB is the max speed of your HTT.
There are several different methods to overclock the HTT and CPU-NB. First way and what should always be done, is just increase the multiplier. No matter what Phenom II CPU you have, you can always increase the multiplier of the HTT and CPU-NB, but there will be a constriction, albeit a constriction you should never see. The other way is to increase the FSB. I will use the 940BE in this example to overclock everything.
Overclock using Multiplier:
200 * 15 = 3000 MHz Core Speed
200 * 10 = 2000 MHz CPU-NB Speed
200 * 10 = 2000 MHz HTT Speed
Overclock using FSB:
215 * 14 ≈ 3000 MHz Core Speed
215 * 9 = 1935 MHz CPU-NB Speed
215 * 9 = 1935 MHz HTT Speed
As you can see, very simple to understand. Now do not start overclocking your CPU just yet. There is still one more section to read before Putting It All Together. In the next section I will talk about the CPU-NB a lot more.
Northbridge
Whenever one is talking about the North Bridge (NB) of a Phenom II, it is safe to assume that they are talking about the CPU-NB. The CPU-NB is a section of the CPU that controls the L3, Memory Controller and the Hyper-Transport (HTT). As mentioned before the CPU-NB and the HTT have different multipliers, please remember this.
When you overclock your CPU, the higher you go the more likely you will need to stabilize the CPU-NB. What do I mean by this? As the CPU increases its speed to calculate data, so must the speed of which the CPU communicates with other components on the Motherboard: chipset, memory, etc. Let me take the classic example of a 4.0 GHz 940BE and its CPU-NB. If you were to leave the CPU-NB at 1.8 GHz stock then the data calculated by the CPU would create a bottleneck and thus resulting in errata errors or CPU errors. So in order to balance these speeds a CPU-NB clock of 3.0 GHz would be needed. In most cases of high OC’s that result in crashes; the CPU-NB is usually the culprit.
I have constructed a table at which your CPU-NB should be at with ‘Y’ CPU Speed. Please note that there is a +/- 200 MHz difference for each step. In order to find your speed without my table, you can use my formula: CPU-NB Frequency (+/-200) = (CPU-Frequency * 2 ) / 3.15.

Highlighted areas are the recommended speeds of which to run the CPU-NB
As you can see with Table 3, these are the support frequencies of your CPU-NB at X CPU frequency. Of course, as you increase the CPU-NB frequency, you have to increase the CPU-NB voltage.
Let me put this in practice, before you start to debate my theorem.

Highlighted areas are the recommended speeds of which to run the CPU-NB
Now that you have seen actual data charts you can criticize my theorem, do not worry I already do it myself. In practice it does not work 100%. Actually I have Super Pi 1M, 3D Mark 06, PC Mark 05 and Geekbench charts as well showing that the 2800 MHz NB usually is top of the charts rather than the recommended speeds by my calculations. Which to me, is fine. The idea behind the formula is a rough estimate of what you should be at with ‘Y’ CPU Frequency.
What you should get from this section is an understanding of the importance of the CPU-NB and how it effects your overclocking process. By all means you should think about looking at the CPU-NB each and every time when try to push for a different CPU Frequency.
Putting It All Together
So now that you have an understanding of how to Overclock your Phenom II, it is finally time to Overclock [rejoice].
If you have an unlocked or Black Edition Phenom II, you can skip the step: “Finding your FSB Max.” For the majority you will be overclocking the CPU by using the multiplier rather than the FSB. This is for most cases and up to a certain percent in CPU Frequency gain.
Finding your FSB Max
First thing to do is find the limit to your FSB [Front Side Bus]. You will increase the FSB by a factor of 10 then by a factor of 5 after that. With each bump, make sure to keep your CPU speed as close to its stock speed. For example if my stock speed is 3.0 GHz which is 15 multi and 200 FSB, when I get to 210 FSB my multi should be 14.5. Same goes with your HT, CPU NB Frequency, and the RAM timings, and ratio. Once your computer does not boot up any longer, this means you have found your FSB maximum. Now you can move on to seeing how far you can push your CPU.
Overclocking the CPU
add in info on using punched in settings for BIOS, and making sure nothing is set to AUTO unless for certain items
For those that have an unlocked multiplier, do not increase the FSB, rather increase the CPU Multiplier by a factor of one and follow the steps as written below. You do not have to worry about the FSB until later on in the game.
Now that you have found your FSB Maximum, you can now push the CPU to see how high of an overclock you can accomplish. Before we begin, you must understand that there will be a limit to the CPU, and you will have to accept it. Depending on your PSU, cooling, and hundreds of other factors, if you try to continuously push your CPU over the max, you could end up harming it. With that in mind let us get started.
Lower your FSB back to 200 stock speed, and bring your CPU multi back up to its stock value. Start pushing the FSB by a factor of 10, and then by a factor of 5. For each successful boot, make sure to run some sort of bench mark tester or stress test. Check the section titled: Benchmarking and Stress testing tools for more information. Once your computer starts to crash during boot or during the benchmarks, you will need to try 1 of 3 different options. Your first option is to raise the CPU Voltage. While this will work for the majority of the time, it does not work all the time. I would first try to increase the Voltage before exploring the other two problems. Your second and third option is to increase the CPU NB frequency and/or voltage. Please use table 3 and table 4 for more information on what NB frequency and Voltage you should be at. You should first try increasing the voltage before increasing the frequency. It tends to work better. You can push the CPU-NB voltage to a max of 1.40v. If you are having troubles with your overclocked CPU instead of increasing the CPU-NB try to bring it down. This same process will work as well with the HTT. For the most part you will not have to do much with the HTT but sometimes lowering it below stock will get you to the CPU speed you want. As a rule of thumb you should keep your HTT between 1200-2200 MHz when overclocking. The third option that you may want to try is messing with your RAM. You can do a couple of things with your RAM. First increase the Voltage from stock by 0.2v. This usually does the trick. You can increase the RAM voltage up to 2.1v or something similar for RAM that is already at 2.1v at stock. If this does not do the trick try working with the Timings and a different Ratio. Sometimes a 800 ratio is better than a 1000, or 1066 ratio and vice verse. Overclocking is not a very simple task. Sometimes it takes time to find the sweet spot for your CPU. Make sure to try a variety of different settings until you feel comfortable. Just make sure to work inside the limits of your computer and the limits I have mentioned in this guide.
As you continue to increase your CPU speed, make sure to watch the CPU temperature. Once it hits a maximum of 60C LOAD, you MUST STOP! You are close to damaging with the CPU if you go any further. If your goal is to make your CPU stable, you NEED to lower the settings to have the CPU LOAD temp at a max of 55C.
Last edited by Dolk; 07-13-10 at 11:29 AM.
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