Question about cooling my PC

My computer case sucks, and I wanted to increase the air flow inside. So I installed an additional fan. The only thing is, I want to make sure that I'm helping my system as opposed to harming it. So I'm basically asking for confirmation that I did this right…

As with all new processors, I have a gargantuan fan plopped right on top of the chip. I assume that it is blowing heat AWAY from the processor.

The only spot for an additional fan was on the detachable side opposite the vertical MB. So I installed a fan which is now blowing outside air INTO the case. There is approximately 2 -3" clearance between this new fan and the fan of the processor.

So now I'm wondering if this is a good idea or not. Am I actually preventing the processor fan from doing its job of clearing heat away, by forcing air right back on itself? Am I making both fans work harder? Or is it good that the door fan is blowing (presumably) cooler air onto the other fan? Would I be better off reversing the door fan and cause it to assist the processor fan in blowing away hot air?

On a side note, the door fan I installed takes a lot of power dips and dives (it doesn't maintain a consistent speed). I don't think there is that much air current in the room, so what is causing it? Is it related to the issues I raised above?

Thanks in advance for input!

You fan on top of the CPU should be blowing air through the heatsink not away from it. Having a case fan near it shouldn't be a problem especially if the fins of the heatsink are not aligned perfectly with the incoming air from the case fan. Even if they are it would most likely not affect cooling performance unless the fan is actually mounted extremely close to the metal it is supposed to be cooling.

Fans sometimes have a power setting and up to 5 variable speeds, are you sure it is not just slowing down once it reaches a certain temperature and speeding back up once it gets hotter? Sometimes this can be controlled in bios but there should be a way or overriding the fan so it always operates at maximum spin speed. These are high end fans I am talking about - if you have a cheap generic one it might indicate that it is faulty or it is not getting enough power via the power molex.

I have included some general advice below, it sounds like you have the general idea already so it may not be helpful.

Any fan you install on a heatsink/air cooler should blow air through the fins of the cooler. There are 3 configurations normally possible.

Push/Pull configuration: This configuration has 2 fans mounted on opposite sides of the heatsink and one is configured to blow air into the heatsink and the other is aiming the same direction which blows air away from the heatsink (sucking air away). This configuration is generally considered the best.

Top down configuration: A single fan which faces down (or sideways) and blows air through the heatsink TOWARDS the motherboard. This configuration is what most heatsinks that come in Retail CPU boxes from intel and AMD comes with.

Single Push configuration: Same as push/pull except you don't have a fan pulling the air out.

For pretty much all these configurations you also need decent airflow inside your case. This is normally achieved by either having vents on at least 2-3 sides of the case or by using an outward blowing fan positioned at the top of the case (hot air rises) and an additional vent near the bottom of the case (as the hot air leaves new cooler air should come in). You could also do this vice versa by having a fan on the bottom vent that blows TOWARDS (into) the case and have no fan on the top.

A high-end case will normally use a push/pull configuration inside the case (which is also called a wind-tunnel). This usually uses 2 large fans (12mm) on opposite sides of the case. This design can also have a tube running between the fans and over the CPU (a wind tunnel).

One thing I'll mention is if you live in a dusty environment, be sure to pull off the CPU fan and check the heat sinks every couple of months. Also check the heat sinks on your video card. If it's a dusty environment, heat sinks can get clogged up pretty bad, and temperatures can soar.

Thanks for the advice. Like I said, my case sucks. It's not a high-end by any means. But it sounds like I have the right idea already, I just needed to make sure. Thanks again!

Or try to get a new case such has this one http://www.xoxide.com/tt-sopranors-101-case.html

that's a pretty nice case indeed

I swear by Antecs. They're not particularly flashy, they're not particularly expensive, and they're not particularly easy to assemble -- but they're easy enough on the eyes and boy do they run cool and quiet. My main rig is in a P180 case, and I've built a couple of Sonatas and Sonata II's.

Word of warning about the P180, though: the power supply is unusually positioned, which means that many/most PSU's won't have long enough cabling to work out of the box -- i.e., take care in choosing one that you know to fit or else be prepared to deal with extensions.

Originally Posted by Jabberwocky
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The basic configuration (in a midi tower case) is to have one fan at the front/bottom blowing cold air into the case (and cooling the harddisks that tend to be fairly hot on modern systems), and one at the back/top blowing hot air out. Many power supplies are designed to help with the second part, which may or may not make any significant difference. If you only have one fan around, use a program like Motherboard Monitor (should be available for free somewhere) to measure the temperature and see what works best. 80mm fans should suffice unless you have a very hot graphics card.

Fans on CPU and graphics card tend to blow air onto the heatsinks.

And make sure that your HDD cables and whatnot dont block the airflow. One can buy special clips to keep them in one bundle at the side of the case, or use string and rubber band like I do… That bird nest can seriously disrupt the airflow.

Originally Posted by Sir Markus
One thing I'll mention is if you live in a dusty environment, be sure to pull off the CPU fan and check the heat sinks every couple of months. Also check the heat sinks on your video card. If it's a dusty environment, heat sinks can get clogged up pretty bad, and temperatures can soar.

Word. Our secondary PC which is about 3 years old had started to bluescreen every now and then, and since I suspected overheating and dried up thermal paste I decided to have a look at the CPU heatsink. The dust layer under the CPU fan was thick and compressed enough to be used as a sponge

We used to vacuum the case every two months or so, but the case has been open during summers in our old apartment that got very hot, and like most Swedish homes it didnt have AC. I guess it would be better to use canned air to blow away most dust before vacuuming, but its a bit of a fuss to find canned air in this crappy small town.

My brand spankin' new gfx card, the nvidia 8800, vents air out the back of the case via the second PCI expansion slot it takes up, so that's good. Still, it runs hot for sure. I need to blow out my case as soon as possible…