Aquired Knowledge

Kamakazi-X's Dual Core Overclock Guide

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Kamikaze-X’s Guide to Core 2 Duo Overclocking



Well, to follow on from my ‘Building an Overclocking PC’ guide, I thought I would put some time and effort into writing a guide on how to overclock a processor, but specifically Intel processors. In this guide I will focus on Core 2 Duos, and particularly the E6600 (because that’s what I’ve got :P).

I would say I’m quite experienced in overclocking, but I’m not a total expert,

and I started on low end processors such as the Pentium D 805, which for anyone interested in getting into overclocking should invest in as a starter project (the processors themselves are dirt cheap). I managed to get it to 4Ghz, and 3.86Ghz stable on air, and it was the 20th highest overclock of a Pentium processor at the time in PCMark05 in terms of points, which I owe to the points I made in my previous guide as well as a lot of patience and tentativeness.

So to start, we have to think about:

Your own Mindset

Overclocking, if you ask the dedicated, is an art, and art is never good when you rush it. If you are the type of person who wants instant results, then overclocking isn’t for you. If you aren’t prepared to spend whole days at a time monitoring your PC, then overclocking isn’t for you. And if you aren’t prepared to spend that little bit of extra cash on a premium component, then again, overclocking isn’t for you.

Next, we have:

The Checklist: Hardware

• A good, overclockable processor. Check the reviews to find out which ones are best.

• A good Aftermarket heat sink and fan combo, such as an Arctic Cooling Freezer 7 Pro. The stock Intel cooler just won’t cut it if you are trying for an overclock above 5% of the stockspeed.

• Aftermarket TIM (thermal interface material). I wouldn’t recommend anything other than Arctic Silver 5 for this, and make sure you know how to apply it properly.

• Good case airflow and cooling. Well, this is pretty self explanatory.

• A good, strong, STABLE power supply. Don’t get distracted by high wattage ratings. If it costs less than £50 then don’t even consider it as an option in your computer. Also, look out for PSUs with a combined amperage of 30A across the 12V rails (see my other guide on how to work this out).

• The right Northbridge chipset. For Intel overclocking, nothing beats the P965, which is streamlined and very fast in comparison to the higher end D975X, which is a little bit too bloated for my liking. Good motherboards with the P965 chipset include the Asus P5B and the Abit Ab9.

• A motherboard that supports overclocking. You might have everything else, but if your BIOS doesn’t allow you to change the frequency of the FSB, then you are royally screwed.

The Checklist: Software

• CPU-Z. Anyone without this program on their computer is just… well…. Stupid. Its probably the most useful spec-listing program I’ve seen out there, and it doesn’t even require you to install it.

• Core Temp. this is a very small, executable file program for Core 2 Duo processors and allows real time, true readings of the core temperatures, and is extremely accurate. You can even mount it in your system tray to keep it out of the way.

• Prime 95. this is EXTREMELY useful in determining the stability of your overclock. It can put a massive load on both cores of your processor (which I will show you how to do in a later section). If the computer doesn’t complete it, then it isn’t stable.

• PCMark05. run this before and after the overclock, and it allows you to see the difference (and helps in stability testing) between overclocks, and also allows you to compare your setup to others. Is also great when it comes to e-peen wavery.

• Your latest BIOS update. Usually helps to have this saved on your computer somewhere, just so you have it there.

• Memtest. Useful in checking memory errors after an overclock.

The Checklist: BIOS tweaks

• Before overclocking, disable anything in your BIOS which you don’t need and could possibly cause conflicts.

• Motherboard vendors usually all have different terms for the same features, but you should disable anything in your BIOS which are along the lines of:

• EIST

• Spread Spectrum

• Limit CPUID Max3

• CIE

• Virtualistion Technology

• No Execute Memory Protect

• Now, make sure that:

• Your PCI-E frequency is set to 100Mhz.

• Your PCI frequency is set to 33Mhz.

• Your RAM is running at its stock timings (it usually says this in CPUZ if you aren’t sure what the stock is).

Now, the Overclock itself:

Overclocking

The aim here is to get the highest percentage increase possible out of your processor, with a respectable target being 15-20%. For example, taking my E6600 from 2.4 to 3.2Ghz is an increase of 19%, and isn’t to be taken lightly. Your memory will most likely be overclocked here too, so you really do have to be careful, or you’ll fry your sticks.

So, first step in an overclock which I carry out is to push my memory. We don’t really want to touch the processor right now, as memory instability is the main cause of a shoddy overclock. You should be using DDR2 800 here, but DDR2 667 is ok and will do the job, but will limit just how far you can get on that overclock. If you have the memory recommended in my previous guide, and a good power supply and cooling setup then you are ready for this next part.

• If your DDR2 is rated at 1.8V (most is), then pump up the volts to 2.1V. if it is rated at 1.9V, then put it on 2.2V MAXIMUM.

• Now, we want to unstrap the memory from the CPU FSB to see how high it can manage. There will usually be an option labelled ‘NBstrap CPU’, and you want to choose the highest rating you are allowed, and see what value it rates the memory at. If it is above 1000mhz, then cut it down to the next. You should be aiming for around 800Mhz here, as when we get to increasing the FSB, your memory clock will most likely increase too to keep up.

Now, try a boot. If it doesn’t, then clear the CMOS and start again (if your BIOS doesn’t allow you to save profiles). Step the RAM down by one more step, and that should sort the problem. If not, then your RAM isn’t too good.

Use Memtest at this point to check the stability of your RAM. Some motherboards really don’t like you unstrapping the RAM from the NB and just wont work, so if this happens to you, don’t worry too much.

Now onto the CPU. I really haven’t found manipulating the multiplier very useful in any overclock that I’ve done, but that may be due to the nature of components in that each one is different to the next, and you wont gain the same results even between identical components due to different batches etc. The stock multiplier on Core 2 Duos is 9 (correct me if I’m wrong) which means that to get the operating speed of the processor, you multiply the FSB speed by 9 (ie the stock FSB of an E6600 is 266mhz, multiplied by 9 gives 2.4Ghz). keep this in mind when overclocking, as every increase in the FSB is multiplied by the same amount as the multiplier.

Now, onto the voltage for the VCore. The stock is 1.35V here, but 1.4V is a more useful voltage as it does in most cases reduce any voltage fluctuations which may occur if the CPU isn’t supplied with enough juice. Most motherboards will allow you to increase the voltage in steps of 0.25 volts, so stick it up to 1.4V now.

Add an extra 0.5V onto your MCH and ICH8 voltage here too, to ensure that they run stable.

On stock multiplier and the settings mentioned previously, my processor can easily handle a 300Mhz FSB, and yours should too. If you are using an E6600, this is already a 10% overclock.

So, put it at a 300Mhz FSB. Keep an eye on your memory, and make sure it doesn’t go too high here (950mhz is a tad too far), as that will limit how much further you can take the overclock.

So, now, carry out some tests for stability. Your overclock should be fine here, but you have to be sure. So, do a PCmark05 run through a couple of times, look for any fluctuations or errors, and make a mental note of any. Then, do a Prime95 Torture Test for at least 10 hours. If done with one instance of the program, it will only run at 50% load on a dual core CPU, so you must follow the next procedure to get to utilise both cores:

• If you run Prime95 and then try to start another copy of Prime95, you only end up with one instance of the program running. In order to run two Prime95 tests at the same time, you need to invoke the program using the "A" command line switch. Make a shortcut to Prime95 and put it on your desktop. Then right-click drag and drop it onto the desktop and select "Create Shortcut Here" to create a copy of the original shortcut. Right-click the copy of the shortcut, select "Properties", and then select the "Shortcut" tab. Then go to the "Target:" field and add "-A1" to the end. If you want to be able to run more instances then create another shortcut copy with "-A2" and so on. Each shortcut will open up a separate instance of Prime95 so you can run more than one test at a time.

• You can check that all of your CPUs are fully loaded in the Windows Task Manager. The Performance tab has a handy CPU Usage History display for each CPU. They are displayed even if you're using hyperthreading rather than full CPU cores. Your goal is to get all of your CPUs running at 100%. If any are less than 100% then you're not doing the torture test at full strength. Running any other programs at the same time will reduce your processor load. It will reduce it even further if a program accesses a disk drive. It's best to run only Prime95 and no other programs if you want to maximize the load on your CPU.

If any errors pop up, go back, reduce the FSB, and see if this changes anything in terms of the test. If it doesn’t, then we need to slacken the timings on your RAM, which will usually solve any errors at this stage.

Most good RAM will be running at 4-4-4-12. however, some may also run at 5-5-5-15. in the first instance, if you are having problems completing prime95 or PCmark05, then change your timings to 5-5-5-12. in the second instance, it should be enough that you can leave them at stock, as the timings aren’t that speedy in the first place. Maybe try adding an extra 0.1 to the voltage on the memory.

Once you have your overclock stable here, and capable of running 12 hours of Prime95 without a single error, then we are ready for the next step of the overclock.



This pretty much entails the same steps as the previous overclocking, but just a lot more tentatively. i have myself manage a 400Mhz FSB on my setup, but I have seen some people only capable of a 333Mhz FSB for some unknown reason. So, increase the FSB by 5 Mhz each time, booting and testing with every increase to ensure that you can indeed boot, and can run the tests fine. This is the most time consuming step, and can take days or even weeks to achieve a stable max limit of you particular setup. It took me 3 weeks to keep mine totally stable at 3.4Ghz, but I’ve throttled it down to ensure stability. Just take the process slowly, keep an eye on your memory speeds, CPU temperatures (you C2D should idle at 30 degrees Celsius and should be no higher than 65 degress Celsius on full load), and that your PWM circuitry isn’t overheating as this will cause fluctuations in voltage going to your CPU.

Remember, testing for stability is the most important thing to overclocking. For example, when I overclocked my Pentium D 805 and achieved the 20th highest spot out of all Pentium processors, I had it rated at 3.86Ghz, and was surrounded by people who had theirs at way over 4Ghz on both sides in the league who were using phase change and water cooling, whilst I had my Freezer 7 Pro. I can’t reiterate this enough.



STABILITY IS PARAMOUNT TO A GOOD OVERCLOCK!



Anyway, thanks for reading this, and if you found this helpful, then it has fulfilled its purpose. If I’ve missed anything, or you have any extra tips on overclocking in general, or Intel systems, then feel free to add them!
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