I'm wondering what the results of users are, who use low to very low RPM case fans (and a low RPM heatsink fan).
Because of my less then stellar heatsink I have to get rid of my "warm" air fast, so I run my case fans at higher RPM's then most here.
At the moment, my intake temp is 21,3 °C. Case temp is 24,2 °C ("idle").
(This is with 2x 80 mm fan @ 2000 RPM).
This is only an increase in temp of 3 degrees, but I've read some users have a delta T of about 10 °C.
[The intake air sensor is placed in the front fan grill (hmm... fan and grill removed, don't know how else to call it), the case temp sensor is placed to the upper part on the metal support for the PSU (the sensor doesn't touch the metal, so it really measures the air temp, instead of the metal temp which would be closer to ambient).]
Is this more or less a guideline, or does it turn out to be like that when you run fans at more or less silent conditions?
PS. I'm starting to worry about the heatsink I ordered about 2 weeks ago, still haven't heard feedback from it, let alone recieve the hardware. No way to start optimising other stuff until I get this new heatsink.
Intake vs case temperature?
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spookmineer
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- Joined: Sat Nov 11, 2006 6:02 pm
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spookmineer
- Patron of SPCR
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- Joined: Sat Nov 11, 2006 6:02 pm
I just installed my SI-97A today and got completely different temperatures.
Although my PC can't still be considered quiet, it's a major improvement. Temps for CPU and MB are almost 10 °C lower (depending on CPU fan RPM) and the sound is almost drowned if I have some soft music on the stereo.
Anyway, the temps I have now are:
Intake temperature: 21,3 °C.
Case temperature: 30,2 °C.
The rear case fans haven't changed.
Suddenly a Delta T of 10 °C doesn't sound insane anymore.
Judging from my measurements, a heatpipe heatsink is excellent for cooling your CPU but it comes at a cost: the case temperature increases considerably.
I don't know if that's a big deal though, the MB temperature has dropped as well (before: CPU: 54 °C, MB: 45 °C - after: CPU: 45 °C, MB: 38 °C).
Although my PC can't still be considered quiet, it's a major improvement. Temps for CPU and MB are almost 10 °C lower (depending on CPU fan RPM) and the sound is almost drowned if I have some soft music on the stereo.
Anyway, the temps I have now are:
Intake temperature: 21,3 °C.
Case temperature: 30,2 °C.
The rear case fans haven't changed.
Suddenly a Delta T of 10 °C doesn't sound insane anymore.
Judging from my measurements, a heatpipe heatsink is excellent for cooling your CPU but it comes at a cost: the case temperature increases considerably.
I don't know if that's a big deal though, the MB temperature has dropped as well (before: CPU: 54 °C, MB: 45 °C - after: CPU: 45 °C, MB: 38 °C).
The heat produced by CPU and other components inside the case is mainly moved out convectively by the air flowing through the case. The difference between air temperature at the exhaust and intake air temperature should be directly proportional to the thermal power of the components. Change of cooler does not affect the heat production of the CPU (at least not significantly).Judging from my measurements, a heatpipe heatsink is excellent for cooling your CPU but it comes at a cost: the case temperature increases considerably.
If the measured case temperature increases after changing the cooler, possible explanation is that air flow pattern and the spatial temperature distribution inside the case has changed. Maybe there's now a warm pocket of air around your case temp sensor. As you told, motherboard temperature dropped, so there is cooler air somewhere else inside the case.
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spookmineer
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Yea... that might be it. My former heatsink was an enclosed Thermaltake Volcano 11+, with tight fins all the way down to the heatsink base. The air won't have a very high speed going out from there.
With the new heatsink, the air can freely go anywhere right after it leaves the raised fins section, so it can get to the sensor more easily. Still, as Forester said, the total heat extracted should be the same, and the average case temp shouldn't be a lot different. Somehow, the colder and hotter parts of air are now distributed in another way because of how the air from the heatsink interacts with the main airflow.
The temperature is the probe type (not related to the MB sensor), connected to a fan controller. It is mounted as described in my initial post, fairly close to the heatsink but more to the front of the case.
I couldn't explain why this happens, but I thought I'd share my findings anyway. They surprised me, but they don't make a real difference I guess. I'd rather have a low CPU temp and higher case temp then the other way around.
My first conclusion is wrong, overall case temp can't change a lot. Hotter air now reaches the temp sensor, whereas colder air reached it in the old situation.
With the new heatsink, the air can freely go anywhere right after it leaves the raised fins section, so it can get to the sensor more easily. Still, as Forester said, the total heat extracted should be the same, and the average case temp shouldn't be a lot different. Somehow, the colder and hotter parts of air are now distributed in another way because of how the air from the heatsink interacts with the main airflow.
The temperature is the probe type (not related to the MB sensor), connected to a fan controller. It is mounted as described in my initial post, fairly close to the heatsink but more to the front of the case.
I couldn't explain why this happens, but I thought I'd share my findings anyway. They surprised me, but they don't make a real difference I guess. I'd rather have a low CPU temp and higher case temp then the other way around.
My first conclusion is wrong, overall case temp can't change a lot. Hotter air now reaches the temp sensor, whereas colder air reached it in the old situation.