Heatsink effectivness

Merlin · Post by **Merlin** » Sun Aug 01, 2004 9:19 pm

Would it be accurate to say that the effectivness/ineffectiveness of the heatsink fan combo can be measured in the difference between load temp and idle temp? Or is it more accurate to say that the difference between case temp and idle temp would be a good indicator of heatsink effectiveness? Please give me the long answer.

T-Shirt · Post by **T-Shirt** » Sun Aug 01, 2004 9:44 pm

Nope!

I don't think you can assume the only contributor to case temp is the HSF.

The effectivenenss of the HSF can be limited by a high case temp, which could be caused by inaddaquite case fans, a high end GPU, etc. The ability of the HSF to maintain a relitively low and unchanging delta (difference between the hot and cool sides) irregardless of the case temp (say 10ºf)would be a sign that it can remove as much heat as the case can absorb.

Merlin · Post by **Merlin** » Sun Aug 01, 2004 10:30 pm

My case temp. is 27'-30'C while my CPU temp. is 40'C at idle so I think its safe to say the HSF can't remove as much heat as the case can absorb. When you say hot and cool sides I assume you mean case temp vs. CPU? If that is what you mean then in a manner of speaking you answered my question with a yes by saying a "delta" of 10'F means the HSF can remove as much heat as the case will absorb. I know high case temps can limit the HSF but if you have much lower case temps. VS. CPU temps. at some point the difference , a high "delta", would tend to indicate that the HSF is not removing enough heat. I don't want to add more case fans if what I need is another, better, HSF and I don't want to buy another HSF if what I need is case fans. Thus my original question. How close to my case temp can I expect a good HSF to get me?

Bio-Hazard · Post by **Bio-Hazard** » Sun Aug 01, 2004 11:30 pm

In my air cooled system my case temps are around 23c - 24c with air conditioning on in the house set at 74F. The idle temps are 32c, but that's with a loud Thermaltake Smart Fan 2 set on high and a Thermalright SLK 800A. Load temp maxes out at 42c running Prime 95. All in all not bad temps but a loud system, I have 6 case fans in the case, 2 in the PSU. My
Copsair does a bit better with less that half the noise. Idle is the same but load hits 39-40c. Not a big differandce between the 2 temp wise, but my Hydrocool is sitting right next to me and I can still hear the other system over it and it's sitting on the floor under a dest at the end of the room...........

To answer your question, I would say that your idle temps should be within 8-10c of your case temps.

LVCapo · Post by **LVCapo** » Mon Aug 02, 2004 1:35 pm

Typically the best you can hope for is a CPU temp about 10-12C over the ambient case temperature (In my personal experience and from what I've read). It should make sense to say that the case temperature directly affect the effectiveness of the HSF in that it cannot cool your CPU below what your case temperatures are, so if you are able to bring the case temps down, it can do nothing but improve the effectiveness of your HSF. I PMed you that link with the chillvent, the review said it improved the HSF cooling by 10C with stock cooling. This should appeal to you in that you have a case with poor air flow, and don't want to mod/cut on the case. You really should look into that as i have hear=d some really good things about it.

Merlin · Post by **Merlin** » Mon Aug 02, 2004 3:54 pm

I got the link. I was just wondering for a little project I am working on. I'll share more about my project later on but in a nutshell its a new cooling solution and I sometimes need little bits of info that don't apply to my current system.

LVCapo · Post by **LVCapo** » Mon Aug 02, 2004 4:17 pm

I like projects!!!! Make sure you keep us up to date on what exactly you are doing.

infinitevalence · Post by **infinitevalence** » Mon Aug 02, 2004 5:56 pm

Heatsink preformace is measued in rise over ambiant at a specific wattage. So if ambiant is 25c and at load a cpu puts off 100w of heat and you have two heatsinks and one keeps the cpu at 35c and the other keeps it at 40c then the first heatsink would have a C/W of .10(Very good) and the second would have a C/W of .15 (Still very good). The thing to keep in mind is that if your cpu only puts out 50w then the difference between the two heatsinks will decrease, the same holds true of the cpu is 150w, the heatsinks will show more of a difference. Hope this helps. feel free to ask me more questions and i will try to explain further if i need too.

Merlin · Post by **Merlin** » Mon Aug 02, 2004 8:57 pm

How would I know how many watts of heat my CPU puts off? Is it based on the voltage going to it?

infinitevalence · Post by **infinitevalence** » Tue Aug 03, 2004 8:45 am

You can always check the manufactures website. You can also use this handy tool at http://www.benchtest.com/calc.html

Using the calc here are my results

Stock Speed : 1866
Stock Voltage : 1.45
Stock Wattage : 45
O/C Speed : 2430
O/C Voltage : 1.95

O/C Wattage : 106
88% of O/C Wattage : 93

The 88% is what you can expect from running your system at full load.
Also on that page is a calc to give you the C/W raiting for your heatsink, just put in your ambiant and cpu tempretures, as well as the wattage of the cpu and it will show you what your C/W is.

Merlin · Post by **Merlin** » Wed Aug 04, 2004 10:32 pm

Mine worked out to be 78 after the 88% deal if I remember right. I know my biggest problem is I need better case fans but no$$$ so I'll just have to live with it for now. I did have a friend cut out two rows of holes out of the front of my WAvemaster, behind the baffel, making two 6"x1/2" slits for the two front fans to pull air from. You can't evn see the slits unless you look for them and I got about 4'C out of it. My CPU temps only dropped by 1 or 2 so I feel sure I need a better HSF. I found a SLK900A for $20.00. Is that good? I don't really have the money but if its a matter of $20.00 now or $35.00 later I'll get the $20.00 now.

infinitevalence · Post by **infinitevalence** » Thu Aug 05, 2004 8:14 am

20 is good, not amazing but still a good deal. Most places are between 30-40 for the same sink. Remember that you will need to buy a fan to go with that, i would recomend sunon, panflo, or delta, depending on the amout of noise you are comfortable with. (panflo = quiet/low flow, sunon = medium/good flow, delta = loud/high flow)

Merlin · Post by **Merlin** » Thu Aug 05, 2004 2:40 pm

I looked at a Sunan 92x25 that pushes 48 cfm for 6.99. the store I looked at was out of the 92mm panaflo that pushes 55 cfm or so.

LVCapo · Post by **LVCapo** » Thu Aug 05, 2004 2:52 pm

HeatsinkFactory.com
[ http://heatsinkfactory.com/cgi-bin/HFAs ... 2mm%20Fans ]

infinitevalence · Post by **infinitevalence** » Thu Aug 05, 2004 2:59 pm

if the price is the same or simmilar i would go for the panflo then as they tend to be quieter, but one thing i like about sunon is the reliablity. We use Sunon fans in all our systems becaues the run for ever.