How I Overclock My Intel Core 2 Duo E6300

For the first time in quite a while (we’re quite likely talking a measurement of years here, rather than months), I decided that I wanted to build a new system. Inspired by two things – posts such as Building and Overclocking a Core 2 Duo System and the utterly abysmal performance of an off-the-shelf HP desktop that I purchased a few weeks ago – I figured it was time.

Up until perhaps three months back, I had been using laptops for the last three years (give or take). This is because I was on the road quite a bit. But since I don’t really travel all that much any more, I figured it didn’t really make much sense to worry about a laptop at this point. Sure, I have a laptop if I need one. But I want to make the leap to two identical monitors. I’ve been using dual screens for some time, and using two that are the same, rather than a laptop screen and an external monitor seems like a good choice.

So I looked about, and found what appeared to be a reasonable compromise – the HP. It came with a video card that had dual DVI outputs, allowing me to power the monitors of choice (more on those another time). Unfortunately, that’s about all it did, and I rapidly determined that my measly single-core laptop seemed to have better performance, so I needed to do something about it. Here’s what I did.

To begin with, perhaps the most important thing you need to know is how hot your system runs (specifically the CPU). For that, you can boot into the BIOS, but that really isn’t terribly helpful, because in the BIOS, nothing is happening – your computer just started up! You need a tool that runs while other things are running. I chose SpeedFan. I also like CoreTemp – though the method it uses reads the temperature directly from the core, rather than the temperature monitor of the motherboard, so you’ll generally see hotter results. See this discussion (it’s rather technical, but interesting).

I tried some other utilities, and some ran while some did not, I liked the packaging of SpeedFan, so I went with it. Find what you like and go with it, but you need to be able to see what is happening while your computer is running under load. It’s vital, so don’t skip this step.

Next up, you need to know how fast your computer is running currently. Again, you can use the BIOS, but the BIOS only tells you the settings – it doesn’t always give you current values, which are important if you have things enabled, such as SpeedStep or other utilities that automatically throttle the maximum speed. Also, if you don’t like to compute the speed of your changes in your head, or you have an older BIOS that doesn’t tell you an effective change, you might want to have a utility that helps out here.

For this, I chose CPU-Z. Unlike SpeedFan, there really aren’t that many options here. This one works, and does a great job. It also tells you useful information about your cache, mainboard (motherboard) and memory to boot. Sweet!

One word of warning – CPU-Z does take a short while to start up, as it has to collect some information. This is true even if you have a very fast processor. However, once running, it’s very quick, and the information updates dynamically – even for processors that change speeds based on the amount of processor usage (like SpeedStep).

With these two tools in hand, you will be able to see what’s happening on your PC.

You might now be wondering why I start with the Intel Core 2 Duo E6300, and you’re certainly entitled. The reason is simple: It’s cheap. It is, in fact, the bottom end of the Core 2 Duo line. As of this writing, it can be had for $181 at Newegg.com (Amazon has it for a couple bucks less). Why start at the bottom? Why indeed. Let me show you.

With my two utilities in hand, I know I can go into the BIOS of my system and bump the speed of the E6300, running on the stock fan, and suddenly my $181 CPU turns into roughly the equivalent of the Intel Core 2 Duo E6700 – a chip that runs not at 1.86Ghz, but at 2.66GHz! Yes, it is true that the E6700 has 4M of cache, but other than that, the clock speeds are very similar indeed. Yes, it is also true that the E6700 could be clocked even higher, but that’s not the point either. Just stick with me for the moment. And all this with the stock fan.

How do I know this? Because I’ve done it. I’m doing it now, in fact. Well, that isn’t entirely true. While I am using the E6300, it’s currently set a bit higher, but I’m no longer using the stock fan, so let me get to that point in a moment. What you need to be aware of before doing this are three things.

#1. Most importantly, you have got to be aware of the temperature of your chip. This is why you need SpeedFan (or something like it). According to at least one page, the maximum cover temperature of the E6300 (in fact, most of the Conroe chips) is 61.4°C. In other words, you want to make sure that the temperature of the CPU itself doesn’t go above this number. In my experience, you can exceed it (or at least, I have), but I wouldn’t recommend doing so on a regular basis.

What can you do to help the cooling of the CPU?

Get some (cooler) air in the case. Many of you may have a desk with a compartment for a computer. Don’t put it there, because it’s stifling. I have seen the temperature drop by as much as 5°C just by moving it from inside the desk to outside. Seriously. Think about it. No matter how many fans you have blowing, if they circulate hot air, it’s not going to help.

Swap out the stock fan. Is this completely necessary? It depends. If you want to bump up the speed a little, no. I changed the processor from a 1.86Ghz to a 2.66Ghz while using the stock fan and had no problems with it. But the processors, under load, hit as much as 65°C – over their rated temperature. Now I’m probably not going to keep them under 100% load all the time, but there you are.

By swapping out the stock fan for even a simple aftermarket Heat Sink Fan (HSF) and some quality thermal compound, I saw temperatures drop over 20°C. That’s a huge change. The cooler the processor, the better, especially when it’s up near the danger zone like that. The 2.8Ghz speeds saw an idle temperature of almost 60°C, and after adding the Scythe Mine and bumping the speed to 2.8Ghz, I had an idle temperature of about 38°C! This cooler, despite not being well-liked, was recently rated well in one of the largest cooler roundups for the Core2Duo chip. It’s long, but a great read.

#2. You will want to make absolutely sure that your new speed is stable. After some changes, your computer won’t even boot. In that case, you know it’s not stable, and you won’t have to worry much. Just reset your BIOS and try something different. But in some instances, you’ll run for a while and have problems later. That’s where testing comes into play. Enter Prime95.

The software is actually designed to crunch prime numbers, but has found a sweet spot for those who like to see if their systems are stable, which is perfect for this process. I’ve heard tell that some people run it for a little while and are okay if it runs through one iteration of results. I typically do that, but then let it run overnight. After the most recent update (to 2.8Ghz), it ran for just shy of 8 hours, and was still going in the morning. I feel confident that things are stable now. Sure, there might be a problem, but I think 100% CPU usage for 8 hours is a pretty good test.

#3. Know when to stop. There is such a thing as too fast. There will always be new chips that go faster, so be patient. Bump the speed up a bit, test it, make sure it’s stable, and try again a little later. But you’re always going to have a ceiling to how far you can push it. Sorry, that’s just the way life is. There are plenty of people who have pushed their E6300 above 3Ghz. I might one day, but at the moment, I’m not going to do so.

Why? Because when it runs at 100% for eight hours, even with the aftermarket HSF, it pushes above 60°C, and that makes me nervous (even if it did so at a lower speed with the stock fan). I know that I won’t run it at that level for that long, but I like to know that it can handle it, and so I know that if I bump it up, I won’t be able to run the test on it without burning out the chip. I don’t like that. If you want to take it further, be my guest. It’s your money.

Also, there is a relationship between the front-side bus (what you’re actually increasing) and the speed of the memory. At the moment, both my FSB and my memory are running at 400Mhz, for a 1:1 ratio. I’ve heard that you can run the FSB faster, but I don’t think I like the idea. I think I’ll leave it like this, at least until I get faster memory. At that point, perhaps I’ll go all out for a better HSF as well. More than likely, I’ll probably upgrade the CPU instead.

So now you think you’re ready to overclock your chip, and you want to know how to do it? It’s actually not that hard. All CPUs (except the Intel Core 2 Extreme X6800) have a multiplier. This multiplier, times the FSB, is your speed. So in the case of the 1.86Ghz speed, my multiplier of 7 meant I had an FSB of 266.7Mhz. By increasing the FSB speed, you effectively increase the CPU speed (which increases the heat, which is why you need to watch the temperature).

My first jump was from 266.7Mhz to 300Mhz, for a modest jump to 2.1Ghz, and this was handled even by the stock fan, but it made me nervous being so close to the failure point of the chip. It is perhaps worth noting that on my motherboard, the FSB is described with a quad data rate (QDR), so it’s actually 1200Mhz, which divided by four is 300Mhz.

The second jump was from 300Mhz (1200Mhz) to 400Mhz (1600Mhz), or 2.1Ghz to 2.8Ghz, and the stock fan immediately saw a balloon in temperature to nearly 70°C right after the start of the Prime95 test, so I immediately stopped it, so as not to damage the CPU. After applying the aftermarket HSF, with the aforementioned drop in temperatures, the test completed and after nearly 8 hours, the highest recorded temperature was 61.5°C.

This is still close to the limit of the chip, so I was nervous. But then I noticed the other problem – my tower was in the desk space. So I moved it into the open air and saw the temperature drop another 5°C, which puts me in the sweet spot. I was even able to turn the fan speeds down a bit. It’s currently running at 34°C, and the chip is almost idle right now, so I’m happy. I have a 2.8Ghz CPU, and I paid just under $220 for it ($181 for the chip, $33 for the HSF and $5 for thermal compound). The going rate for that X6800 is $975. Sweet!