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High case and cpu temps even with side panel open

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shiksotalik

New Member
Joined
Nov 28, 2003
Location
San Francisco, CA
I was trying to quiet down my stock p4 3.0 in a full tower chieftec monster case, so I did the following:

- Replaced stock 80mm chieftec fans with 80mm pc power&cooling silencers (2 front intakes, 1 side intake, 1 rear exhaust). The silencers should be 20dB, 27cpm, but seems like everybody is skeptical about 27 cpm.

- Removed the stamped out grills in the front and in the back. Put some spun fiberglass AC filters on the intakes.

- Replaced the stock HS with Zalman 7000 AlCu, no lapping, just cleaned with isopropyl alcohol and used the thermal goop that came with the Zalman.

Well, things did quiet down, but MBM5 was reporting 35C cpu / 32C case idle, 51C cpu / 37C case under full load. I figured the silencers were sucking more (or rather, less) than they should have been, and removed the side panel. The temp drop was pretty negligible: 33 cpu/31 case idle, 51 cpu /36 case under load.

So now my question is... What did I do wrong? I'll get some AS5 and will reinstall the HS, but this won't drop the case temps. I could put in another 80mm exhaust fan in the back, but I don't want negative air pressure in the case. The airflow in the case should be ok, all the cables are tied down along the walls.

Anything else I'm missing?

My system is a stock p4 3.0 (no desire to overclock, just want cool and quiet), intel 875PBZ mobo, radeon 9800pro with stock cooling (will deal with when this is resolved), chieftec 420Wt PSU with 80mm intake fan on the bottom, 80mm exhaust fan on the back (both are pretty quiet).

Any suggestions about cooling AND further silencing without major case mods (need to be able to revert to native state for warranty purposes) will be much appreciated.
 
Ok first of all removing the side panel is not a good idea as it disrupts the airflow of your case...air drawn in goes out the side of the case rather than pushing air out the back. you might want to change your side Intake fan and change it to an Exhaust, I did this and got better performance. (As you have 3 intakes and one exhaust)

What you also have to remember is if you want silince you have to be prepared for slightly higher temps although looking at your temps they seem extremly good to me!

Also change the thermal compound as the white stuff you get with most heat sinks is rubbish.
 
Well, the PSU counts as an exhaust too, right? So I have 3 intakes, 2 exhausts now. Making the side intake into exhaust would leave me with 2 intakes, 3 exhausts... And the actual airflow balance would be even worse due to the air filters on the intakes. Is my reasoning off? Just don't want to vacuum the case too often...
Oh yeah, the side fan is at the GPU level, does it make more sense to blow at the radeon or suck air away from it?
 
And I was hoping for sub 45C cpu / 30C case load temps... I guess this might be unrealistic with my slow quiet fans...

Also, the airflow around the case seems to be fine (not stuck in the corner), there are no heater vents near it, room temp is and will be 21-22C at most, I'm in the foggiest part of San Francisco...
 
ok although Your PSU draws air out of the case the actual heat that it produces negates any benifits this would have due to the PSU actualy heating the inside of the case as well as the actual case frame it's self. If your lucky your case will have a hanger for the PSU so it's not actualy in contact with the outer shell of the case.

As for GPU fans i found i got better results drawing air out of the case rather than blowing in. As It removes the heat from the case straight away while a fan drawing air in just circulates that hot air around the case till it can be removed by your exhaust. Also it means you need one less filter cover and can have the fan running at a higher setting.
 
To expand on what FarEast said. As it stands minus the PSU fan you have roughly 81cfm blowing into the case and only 27 blowing out. That’s figuring all the fans are the same. Even if you factor in for a possible 5cfm loss due to the filters. This would still be 66 in and only 27 out. In order to have good negative pressure that doesn't hinder airflow in the case. You want between 5 - 10cfm difference max from the exhaust to the intakes. The side fan could also be creating airflow disturbance by blowing inside the case. This could make it harder for the single rear fan to move it out. You could try this. Take the side fan and attach it to the rear of the case then plug the side hole up with something (Like a small hand towel). Then test to see how your temps are doing. :)
 
They have you covered.I couldn't have explained it better.They know what thier talking about. Cheers THE FANMAN:cool:

NOTE:You keep answering your Q.Quite fans dont move much air!!
TEST:Blow out softly /not much air ,,not much noise
Blow out real fast,,lots of air / more noise,,,Test Complete!!:)
 
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To confirm that it is airflow causing the problem, take the case panel off and blow a large desktop fan in the side of the case. If the motherboar case temperature doesn't compare well to actual room temperature then you have dodgy sensors.
 
You might need what Intel has specified, a "Thermally advantaged" case. All this is, is a duct on the side panel that lets the CPU's fan draw air directly from the outside of the case, rather than drawing air from inside the case.
 
Thanks for all the replies...
To reiterate my goals: I want a quiet, decently cool comp with minimal dust accumulation. Cool enough to run at stock, no overclocking is planned in the near future.

FarEast and Sharkman:
I'll try out [2 rear exhausts and no side fan] and [1 rear exhaust and 1 side exhaust] and maybe [2 rear exhausts and 1 side exhaust or intake] combinations tomorrow when I get back to town. But humor me with some answers if you can:

I do understand that the PSU does nothing for cooling (it's exhaust is pretty hot as it is now :) ), but it does contribute to air balance. If I have 3 exhausts (PSU, side, rear) and only 2 intakes, and all the fans are the same except for the PSU, I'm definitely creating negative pressure in the case. Then there's no point in using air filters on the intakes, since the dust will be sucked into the case through every small hole, not just the intake fans. I thought the point was to avoid negative pressure and prevent dust buildup. That's what I want to accomplish. Tell me if I'm wrong.

L337, FANMAN, FarEast:
Right... Slow quiet fans -> not so good at cooling. BUT, as I've said, with the side panel off the temps don't drop at all. (I have no large fan at home to blow at the open case, I'm in San Francisco after all... ) I thought this indicated the that the poor airflow inside the case is not the culprit. FarEast, even if the airflow is disturbed by the open side panel, it should still result in better cooling (no side panel = large area for passive convection), no?

CrystalMethod:
Any advice on the parts I need to connect 80mm fan hole on the back of the case to Zalman 7000?
 
hey shiksotalik, i might have a few suggestions for you.

you want no dust and low case and cpu temps and silence, right? ok, silence is really the kicker here, because if you didnt want that, the other 2 would be so easy to get. basically, my main suggestion is to either use a curved duct to get airflow from the rear of the case onto your HS, as crystalmethod suggested. search "ducting" on the forums to find examples of how to do this.

another thing that may help is to put an exhaust at the top of your case, because that's where all the hot air accumulates anyway. if you have 1 exhaust on top, 1 psu exhaust, and 3 intakes elsewhere, your pressure should be positive, which is what you want. i suggest nesting 2 intakes into the front grill where the insulation can be hidden and can dampen their noise. the other intake can be the one used for your HSF on the side or back of the case.

maybe look into getting a 4-fan rheobus to turn the noice down when it matters, like at night. i think i got at what you are looking for. all the guys above me had good answers too though. this is just my 2 cents.

good luck
 
hmmm im probably wrong but it just sounds like his system temp is reading to high, becuase the difference between his cpu and and system temps and very small, and his cpu temp seems about right.
 
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