Hello,
how many fans would i roughly need to keep an overclocked pc cool?
There are several variables involved in overclocking. Your case, voltage, clock rate, and environmental variables will vary. Essentially what Z1NONLY is trying to explain; is that overclocking is creating faster performance. By creating this boost; your pushing more electricity which creates more heat.
So overclocking becomes a fine line; performance + temperature = stability.
The reason I'm expressing it in the form of a mathematical formula; is because increasing either of those two variables will directly impact your stability.
So when you increase voltage; your increasing current. Which will now generate more heat. By having more electrons circulating for calculation you generate more heat. Heat eventually will create issues; which will cause it to overheat and or fail. So your ability to dissipate is important.
Now that I've explained how the variables can impact each other, these are important for successful overclocking.
1. Your Central Processing Unit (CPU) - Each processor is different; each attainable speed may vary. As some may have more or less silicon. This can help offset that increase in heat. So your processor will have it's own power and thermal inductive limit.
2. Random Access Memory (RAM) - Your memory is just as vital as your processor. As your CPU will perform the calculations; which will provide your performance. Your memory's ability to store the data in it, then send it to your processor. The faster they can exchange information which will allow calculations to occur more rapidly.
By overclocking these items; if it is pushed too far you may create system instability. Too little; may actually become less efficient. The goal is to optimize both, the less electrical circulation with the highest calculation rate becomes the best form of overclocking. As it creates the most power per watt.
Now to your original question. How many fans would it take to keep your overclocked machine cool?
As I stated above, you have all these variables to consider. Each one will affect your outcome. But overclocking your machine will generate significant heat. The inability to dissipate or transfer heat will cause the failure or crash.
1. Your case, certain materials will retain heat more then others.
2. How much cooling can you put into your case?
3. Room temperature, a hot room can also impact your machine.
4. Significant moisture in the air
All of those items can impact how much heat your machine will generate. You'll have to effectively cool your components.
An example:
Case: Antec 1100 Case ( Seven Fans )
Cpu: i7-920 (After market Heatsink / Cooler (Two Fans))
Memory: Mushkin Redline Enhanced ( Memory Cooler ( Six Fans) )
GPU: SLI GTX 580 (X2) - Enhanced GPU Coolers. (Six Fans)
Then I've modded my case with an additional six fans. The fan selection was always based on the highest CFM's and RPM. The more air it can push, the faster it does it. The better your heat dissipation will be.
That machine above is overclocked; very heavily. The CPU's idle temperature is 23-26 degree's Celsius. Under load it hits about 60-70 degree's Celsius. My graphics cards idle around 30-35 degree's Celsius and my under load hit around 65-75 degree's Celsius.
CPU Stock: 2.6 GHz
CPU Overclocked: 4.6 GHz (4.9 GHz Turbo)
GPU Stock: 772 MHz
GPU Overclocked: 960 MHz
You can see the gains; the gains are there. However something that is often overlooked; especially with keeping your machine cooled while overclocked. Sound; my machine under load has the better amount of six to ten fans spinning at 3,400 RPM's. It can get really, really loud.
These are all things to consider; this is why Liquid Cooling and Sub-Cooling are so effective. They cost more, but tend to dissipate heat more effective and are quieter.
Hopefully I've provided you with several important details to consider in your choice. If you need more assistance, please let us know. The community would be happy to assist.
Just remember, limit your variables as you overclock. That way you can optimize your performance and cooling to attain the best numbers.