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Pedal to the Metal: Overclocking the Athlon

Author: Atif Butt
Subject: Processors
Manufacturer: AMD
Tagged:

What Will I Need to Overclock?

AMD Central Processing Unit (CPU)

Yeah, I know, you weren’t planning on overclocking with a donkey. Then why did I include this obvious requirement here? The selection of a CPU appropriate for overclocking involves a bit more than grabbing the first box that catches your eye at the store. There are a number of factors to consider, only one of which is the obvious “how much does it cost?” I’ll cover the four factors I think you should consider when shopping for an overclocker-friendly CPU.

1) If this was 1996, chances are you wouldn’t be trying your hand at overclocking due to the risk involved in modifying your newly purchased hardware. If you were overclocking back then, you were a trailblazer, living on the edge with little/no idea of what to expect from your adventure.

One of the benefits of overclocking gaining mainstream acceptance is that hardware enthusiasts can openly discuss tips and troubleshooting advice with one another at a number of websites.

Overclocker databases (banks of user entries detailing how an overclock was achieved), community forums and support websites all can help answer an important question: what kinds of overclocks are people getting with a particular CPU?

If you consistently find that a particular CPU is achieving phenomenal overclocking success; that CPU should be on your list of purchasing candidates. If you want to get opinions on what type of overclock to expect with a particular CPU you were already eyeing, you can post such a question in a community forum and gain some valuable insight.

In addition to using community-driven forums and overclocker databases, you should definitely pay mind to professional hardware reviews that cover overclocking potential of CPUs. If you find that a particular CPU overclocked well in a number of reviews, again, add it to your list of purchasing candidates.

2) Now that you’ve got your purchasing candidates, if you’re anything like me, chances are you’ve established a novel-length list. We’ll need to pare that list down to a manageable size such that a CPU can eventually be purchased.

We can start paring down the list by answering the following question for each CPU on the list: What is the CPU’s stock speed? We need to gather this important data along with information on the overclocks people are getting for each CPU.

By compiling this information, we can establish the degree to which people are overclocking each CPU. For example: if a CPU on the list of purchasing candidates has a stock speed of 2.0GHz and was overclocked to 3.0GHz, this indicates a 50% overclock over stock frequency.

It is important to note here that some overclocking expectations must be tempered immediately (in particular, those that rest on the overclocking results of one individual).

Let’s assume that a CPU has been on the market for a while, and people have generally attained a 20% overclock with this CPU. If one individual reports a 40% overclock with the same CPU, we should take this as an exceptional overclock, but not representative of the norm.

On the other hand, if a CPU has just entered the market, and an individual has posted only a 5% overclock, wait until more people have had a chance to purchase/overclock the same CPU before removing the CPU from your purchasing candidate list based on its apparent inability to overclock.

As a general rule: unless there is overwhelming evidence to suggest that a lower-clocked CPU is consistently achieving high overclocks, go with a CPU on your list that has a higher stock frequency and regularly attains an overclock acceptable to you.

This way, even if the overclock you achieve is small/negligible, you’ll still have a CPU running at a frequency capable of handling whatever you might throw at it.

3) When narrowing your list, you may find two similar CPUs (as far as cache, core frequency and price are concerned) that differ only in their manufacturing process. Does the manufacturing process of a CPU affect overclocking?

First, we need to discuss what the “manufacturing process” refers to. CPU manufacturers use “manufacturing process” to refer to the measure of the smallest printed feature size in the CPU (i.e. the transistor gate length). As this feature size is reduced (through smaller manufacturing processes), it allows for the packing of additional transistors per unit of physical space than previously possible (see figure).



 

Figure 1: Using an older manufacturing process, as on the left, may have allowed for the inclusion of two transistors per die. The newer manufacturing process, on the right, allows us to fit more transistors on the same die.

Since the gate length of each transistor is shortened, they operate faster than before. Further, since the transistors are closer to one another, switching between transistors is also speedier. As a result, a higher operating ceiling can be reached. Though this clearly bodes well for overclocking potential, a smaller manufacturing process does not guarantee a significantly higher overclock.

This is not to say that a CPU manufactured on a smaller process is one that you should avoid. Certainly, a CPU manufactured on a smaller process is sure to afford certain benefits in the areas of heat output and power draw that anybody (overclocker or not) can benefit from.

Still, don’t expect a CPU coming right off the assembly line to yield an astronomical overclock just because it is based on a new manufacturing process. This newer process may very well offer tremendous overclocking potential, but some time is usually needed for the manufacturing process to really shine.

4) Once you’ve done your research on which CPUs show the best overclocking potential based on first-hand experience, % overclock above stock speed and the manufacturing process employed, the only question that remains is: how much does the CPU cost?

You could have a mini-dilemma in the following situation: an $80 2.2GHz CPU on your list of purchasing candidates regularly achieves a 3GHz frequency and a $120 2.6GHz CPU hits the same 3GHz speed.

It would be wise in this case to consider the following: while saving $40 upfront by buying the 2.2GHz CPU, you are taking a gamble that you’ll be able to achieve a slightly more difficult 36% overclock to reach 3GHz as opposed to the 15% overclock necessary to hit the same speed with the 2.6GHz CPU. The question you should ask yourself is: would you be happy with the 2.2GHz CPU if it didn’t hit 3GHz, or would you regret not buying the 2.6GHz part?

Because overclocking potential can vary wildly from one CPU to the next, it is entirely possible the 2.2GHz CPU will reach 3GHz while melting your room in the process. Alternatively, the 2.2GHz CPU might have more overclocking headroom than the 2.6GHz part you’re considering. In any case, the added strain on either CPU will demand that an adequate cooling solution is used to funnel away excess heat.

For this reason, when you go CPU hunting, you’ll want to factor in the cost of a performance cooling solution into your final decision. Performance coolers cost good money. When all is said and done the $120 2.6GHz CPU could be a so-so overclocker and require an aftermarket cooler to hit that 3GHz mark, driving up the total cost of your system in the process.

For obvious reasons, the selection of a CPU can be a difficult task in any case. When a CPU is being purchased with the express intention of overclocking, it becomes more difficult to select a suitable part. Still, effective research on the types of overclocks people are obtaining with a particular CPU (including its various revisions), and cost can help make this difficult decision slightly easier.

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