how important is rise over ambient?

[IlllI]

after reading many reviews on various heatsinks, i am still not exactly sure what it is, or how important it is in regards to heatsinks, cooling, and overclocking. i notice that a lot of reviews just kind of skip over this and dont really say why its important. can anyone give a good description of how/why this is important for cooling?

 

[Cerb]

With air and heatpipe cooling, you can't get the case and CPU below the ambient temp. So if it's summer and you have the window open, you can't get the coolest part of the PC under 100F, where inside w/ AC going you can keep it under 80F.
So the hotter the ambient temp is, the hotter all the parts will be. If you have a CPU reading 40C, that's great...but if the ambient temp is 25C, it's not that great. If the CPU is 40C and the ambient is 30C (and case temp 33C or so), you've got some great cooling.

 

[IlllI]

ok, but how does a heatsink specifically affect the rise over ambient temp? from what i gathered, it plays a major part in it...well at least thats what i assumed... usually when i see reviews about heatsinks there are graphs/stats showing the cpu with : max load, idle, and rise over ambient (well something like that)

 

[Blain]

Rise over ambient is the most important thing to look at when comparing HS (apples to apples).
As long as you compare rise about ambient, you will see which HS cools the best.
Fan noise is also something you need to take into consideration. HS A may have better test results over HS B. But HS A may have done it with 60dBA vs. 30dBA of HS B.

Unless water cooling is chilled, the best it can do is get you down to ambient.

 

[mindwreck]

the higher the rise over ambiet, the poorer the heatsink performs. remember to check the ambient temperature since it changes from review to review and room temperature.

 

[daba]

Well it really comes down to this:

If you have an AMD: Thermalright SP-97

If you have an Intel: Thermalright SP-94

 

[IlllI]

thanks for al the info. the only thing i knew was that the lower the number, the better. however, i never knew why, nor did i know how the hs played a part in determining the rise over ambient