faster system fan blowing in CPU=less temps, NOT!

newdude · Mar 3, 2005

I had a regular 2800 rpm case fan blowing on my CPU to help with keeping the temps down. So I thought hey lets put in a thermaltake smartfan 2 that is currently running at
5110 RPM. Guess how much it lowered my cpu temps, one degree. Well Now i have a faster and noiser case fan but not much of a cooler cpu. Maybe I'll put a funel on and see if that helps.

Edited by newdude on 03/03/05 05:09 PM.

newdude · Mar 3, 2005

Well it lowered the temps about 2 degrees. I think my cpu just running cool as it's going to get without actually blowing colder air on it.
Right now it's 29 degrees. And the cpu fan and heatsink is a 60 mm fan, were the case fan is 80mm. the case fan runs much faster that the case fan, I guess I need to have a cpu fan that runs at the same speed to suck in as much air on the cpu as the case fan is blowing in.
Edited by newdude on 03/03/05 05:55 PM.

Rugger · Mar 4, 2005

The HSF is moving hot air away from the CPU - not onto it. You could try making the rear case fan your intake fan and the front fan your exhaust fan. That way your intaking cool air and blowing it right into the area of the CPU.

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newdude · Mar 4, 2005

Hold up, Now i'm completely confused. ISn't the cpu fan blowing air on the CPU chip not sucking air out. I mean whenever you see a case fan on the side isn't it blowing air on the cpu area. Isn't the object to get cooler air to blow on the cpu to cool it off.

Edited by newdude on 03/03/05 06:30 PM.

Rugger · Mar 4, 2005

HSF: The heat sink draws heat from the CPU and then dissipates that heat into the air. The reason you have fins is to make more surface area for the heat sink to pass the heat into the air. The fan on the heat sink then draws the hot air away from the heat sink.
Case Fans: Purpose is to create an air flow by intaking cool air with one fan and exhausting air with the other fan.

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shawnlizzle =] · Mar 4, 2005

very good answer dude, but also know that 1 or 2 degrees drop is a pretty good performance boost. also, we don't know what cpu you have or what kidn of ventilation you use so, we can't really help you that much if you don't provide these info. on a side note, if the fan that is on top of the heat sink has a very big center, then it is not effectively pulling air away because there is a dead spot in the middle of the fan. just remember rpms don't mean everything.

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newdude · Mar 4, 2005

What do you mean by having fins, could you expalin more?? Is this the blades on the fan?? Is the cpu fan blowing air on the cpu or sucking air of. I have a side case fan blowing air onto the cpu and a fan on the back sucking air out. I also have a case fan blowing air on the video card, and a fan sucking air in on the front bottom of my case. sorry, I have a athlon 64 3000 socket 754 newcastle design.

Edited by newdude on 03/03/05 07:01 PM.

newdude · Mar 4, 2005

and the cpu heatsink and fan is the one that came with the cpu retail. Don't want to change the cpu fan or heatsink because it'll void the warinty. Besides I'm not concerened about the temp geting hot the temps of my cpu right now is 28 degrees. Just i like to see how cool i can get my cpu with the least amount of cost. couple of weeks ago I just a box fan in the window and turned the fan on high and aimed it at my case. within a minute I had the temps down to 18 degrees. probally could have got it down more if it stayed longer. I even thought about building/ or gettin a case that i can put a small box fan on the side. I have a box fan in my house and it's quiter than my case fan. I'm going to put a funnel on the case fan blowing to the cpu and see what that does. I'll also trying switching the direction the fans blow on my rear fan and side cpu case fan.

Edited by newdude on 03/03/05 07:10 PM.

newdude · Mar 4, 2005

so in theory if i put a bigger cpu fan on the heatsink it will displace more air for the heat from the cpu to draw away from.

Rugger · Mar 4, 2005

Tell us exactly how many fans you have, location, size (80MM, 90MM, etc) how many CFM (cubic feet per minute) they move and what direction they are blowing - into the case or out of the case. To test the direction your HSF is blowing you can use your hand, piece of paper or the feather you use to tickle your girlfriend. :evil:

HSF = heatsink and fan. Heat sink touches CPU and a fan sits on top of the heat sink. The fan that is on the heat sink should move air away from the heat sink and CPU. The fins that I'm talking about are the metal ridges or blades of the heat sink - not the fan blades.

"newcastle design" Newcastle is the name of the CPU core.

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shawnlizzle =] · Mar 4, 2005

well, this again shows that rpms arn't everything. case fans arn't designed to keep your cpu cool, it is designed to keep your case cool(the inside...duh). so to maximize this effect, i would suggest 2 intake and 2 exhaust. other then that, tie down your wires or try to get rounded wires to allow for more airflow. doing these things will keep the temps down a lil, but don't expect it to cool your cpu that much.

One Lowe

newdude · Mar 4, 2005

I have a 80 mm intake fan on the bottom front of my fan, not sure what CFM is but it's a basic 2 dollar case fan from ebay. I have a 80mm regular case fan blowing air on my video card. And a thermaltake smart fan 2 case fan blowing air on my cpu. I have one exsust fan on the back of my case blowing air out and My thermal take powersupply fan with adjustable speed sucking air out of my case to. I'm thinking about putting a case fan on the top of my case to suck air out because i've noticed that heat seems to hibernate to the top were all the wires are and stuff.

shawnlizzle =] · Mar 4, 2005

my suggestions for lower temps:

-use the 2 intake, 2 exhaust formation.
-GET BETTER FANS(more air flow, pressure)
-you have a case fan on your cpu? get ride of it and get a regular hsf, i suggest the zalman 7000 or 7700 copper
-tie down wires or get round cables

if you follow those guidelines, you should be fine

One Lowe

newdude · Mar 4, 2005

CAN i get a new heatsink and keep the same fan, just for money issues. Or would it be best to change both. I'm on a limited budget so price can be a issue.

newdude · Mar 4, 2005

okay one more quick question. If the object of the cpu fan is to push away hot air away from the cpu so theres no build up of hot air over the cpu then how does your case temperture also determine the cpu temps if none of the case air is getting to the cpu due to the fact that the cpu fan is pushing air away from the cpu. Why then when i put my box fan in the window and aimed it at my computer case and turned it on high did my cpu temps go down so low on my cpu. I just want to make sure I understand this correctly. I'm not trying to be sarcastic I just want to understand the idea of cooling. I would also like to see how the air flows in my case can you use like smoke or something so you can visualy see how the air moves in my case.

Edited by newdude on 03/03/05 08:47 PM.

shawnlizzle =] · Mar 4, 2005

the cpu has a pin for temp dude.... and the fan question isn't very legit... what if i asked you, why does my comptuer run cooler when i dip it in liquid nitro? and blowing smoke onto your system is

a)not smart
b)will fill up the room in smoke in a matter of minutes
c)the smoke will only give you info(if any at all) the first few seconds of activation because you can see a contrast in the air and the smoke

so don't do it =]

One Lowe

newdude · Mar 4, 2005

then theres really no way of telling how the air flows in the case. Another thing is okay if the object of the cpu fan is to puch the hot air away, how about putting an extra fan on the side of the CPU to help push air away from the cpu and toward the rear fan to blow the hot air out.

shawnlizzle =] · Mar 4, 2005

you kinda know how the air flows in the first place - air comes in the front and exits in the back =D. the fan above the HSF will help, but it depends on what HSF you have, if it is centrifugal, the it wouldn't help, but if it pulls air up like normal HSFs then sure, go ahead and try.

One Lowe

newdude · Mar 4, 2005

okay first of all what is centrifugal. second would a regular case fan attached to the side of the cpu help displace air. should it be on the right side of the cpu blowing air away or should it be on the left side sucking air away??

Rugger · Mar 4, 2005

Let's get back to basics before we, the collective braintrust of the THG forums have you buying and moving fans from here until teh cows come home. What is your case temp and what is your CPU temp at full load?

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endyen · Mar 4, 2005

temps of my cpu right now is 28 degrees.

Reality check. What is this whole thread doing. Are you going to try to get a modern chip to power up a chilling unit? There are physical laws that apply here. The chips going to put out heat. That heat can only be displaced so fast, esp with air cooling. There are people out there who would like those numbers, who are using liquid cooling.

Rugger · Mar 4, 2005

To be honest I think it's more likely that 29C is the case temp and he has a load CPU temp around 50C. =/ He just needs to confirm that to us and we can be done with this thread.

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mozzartusm · Mar 4, 2005

The funnel will probably help if you design it properly. I agree that you probably do have circulation issues.

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mozzartusm · Mar 4, 2005

You are the first person here other than myself that I have seen suggest reversing the rear fan. Its the first thing that I do when I am building a new system. Especially when you have a 120mm fan on the front and back of the case it can really make a difference. I dont know why this isnt talked about more than it is.

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Rugger · Mar 4, 2005

:redface: I actually got the idea from you. Great idea! Actually did it on my current system and got a 1.5C drop in temp.

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faster system fan blowing in CPU=less temps, NOT!

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