Shouldn't water cooling Temps = 1 degreee more than air?
 

? I have is that shouldn't CPU temps with water cooling be just one or two degree's more than inside case temps?
Providing that everything is mounted correctly, etc.
and Rad is properly cooled.

Thanks for your input.

Re: Shouldn't water cooling Temps = 1 degreee more than air?
 

That doesn't make any sense to me. The CPU heats the Water, the water is cooled by air, most likely air coming from outside the case. The CPU heats a block which heats the water, which is cooled by the ambient, external air.

So the water should be a few degrees above ambient. The CPU will be warmer than the water by an amount determined by the C/W of the WB.

I think, anyway. Does this make sense?

The CPU is going to be hotter than the block, which will be hotter than the coolant, which will be hotter than ambient. If you can get your CPU die temp to within 5C of ambient, you've got an OUTSTANDING system, though most see a 10C+ temperature difference depending on their system. The temp differential is what allows heat transfer to take place. If everything is about the same temperature, nothing would happen, and the cooling system would be unnecessary. Since we know that isn't the case, it becomes obvious that the CPU will run quite a bit hotter than ambient.

The only way to get near or subambient cooling is to use active cooling like pelts, a good bong, or phase change.

Things that affect water-cooling's performance:

1) The thermal paste interface between the CPU and the waterblock. This is proportional to the area of the CPU is is typically around 0.1 C/W for a 100mm^2 die size (and consequently around 0.08C/W for a 125mm^2 die size like an AthlonXP). For every watt of heat that a Palomino AthlonXP CPU dissipates, the CPU will rise by around 0.08C. A really really hot Pally XP can dissipate up to around 85W (real watts), meaning that the CPU will be at least 7C above ambient merely due to the thermal junction between the CPU and the waterblock alone.

2) The waterblock's native cooling performance - this hinges on a few factors such as flow rate and design, with the best blocks offering C/W's of around 0.07 for a 100mm^2 die size, and as bad as 0.25 for a poorly designed block with low flow through it. We can't really relate this to die size in actuality, but for simplicity sakes let's do it anyway. Assuming you used a Pally AthlonXP in a highly overclocked full-load scenario using say a very good block with a decent pump, you might be seeing a C/W of around 0.10 for the block and the AthlonXP sized die. ie. the CPU will climb to around 8.5C hotter due to the waterblock's performance. Note that the waterblock's performance is affected by the temperature of the water flowing through it.

3) Pump heat - the pump will dump heat into the water which needs to be dissipated by the radiator. A typical pump will add around 5-10W of heat to the water. This is handled by 4) below.

4) The radiator then needs to cool the water. A very good large radiator with high speed fans will offer a C/W as low as 0.02, but realistically a 0.05 C/W is a far more common story for a noise bearable radiator that fits inside most people's cases. Given the 85W that the CPU puts off plus the 10W of the pump, and multuply that by 0.05, and we get water temps that will sit at around 5C above ambient.

Add all that up and we get 7 + 8.5 + 5 =~ 20.5C CPU rise above ambient for a very hot CPU.

Just all rough and simplistic of course. There are quite a few other factors operating here (motherboard heat/motherboard heat dissipation - commonly called secondary heat paths), radiator intake temperature which can be higher than ambient especially if the radiator is mounted in-case, etc.

He's comparing cpu to temps inside his case, not ambient. This could throw a big wrench into the equation. I can see how it would be possible to get a cpu reading lower than case temp reading. Whether or not the readings are correct is a different story. My cpu is always reported at 6C above my case temps. A lot would have to do with airflow in the case and where the temp sensors are located.

peace.
unloaded

Yeah, when doing C/W formulas for my system (not just block) I've always been heavy on lowering CASE ambient, cause that really effects the starting temp point at which your radiator is, meaning if your radiator is outside case, then it's naturally going to be cooler than in case, which makes sense, but inCASE units suffer from latent heat from HD's, mobo, and chipsets etc... And like me, most people have their's barely fitting underneath some hot spinning 7200's, plus the incoming air cools only the internals of the HC/Rad and all that latent heat around the HC/Rad just sits and bakes it like an oven... Most ppl say that it's negilable heat increase, but I've recorded differing results...?

One note; when I'm doing C/W temps I usually don't include pump heat, should I (Der?!) eg: XP 1600@1814/1.792Vcore =
~85.323W.

38Cmax - 24.5Camb = 13.C, 13.5C/85.232 = .158

35Cidle - 24.5Camb = 10.5C, 10.5C/85.323 = .123 (hehe)


W/Pump Watts added: (~10W)

38Cmax - 24.5Camb = 13.5C, 13.5C/95.232 = .142

35Cidle - 24.5Camb = 10.5C, 10.5C/95.323 = .110

Note these may not be totally accurate, but for estimates sake...


:)

If you said ~55W instead under the most stupendous full-load application you could possibly run, then you'd be much closer to the truth of what said CPU's heat output is in actuality.

A real 85W CPU is something like a Palomino AthlonXP running at 2.0GHz at 2.20v Vcore running BurnK7.

This is the input Im looking for.
I have read on many forums that people have there Rad inside the case and that there INSIDE Case Temp is just a few degree's lower than CPU Temp.
If I can accomplish this I will be very Happy.

I have good quite air flow right now, 4 fans in my Antec case. Im going to try to First put Rad in case and see how that goes.
If Im not happy with results I will build a house for the Rad and Pump.

*Good air flow inside case, I think is the key. I wish I had or could think of something that is cheap, under $100, that could create cold air. I would then run a 1" or 2" tube inside case and push that cool air into case.

I will think of something !

So the MAIN limiting factor of a WC system usually isn't the Radiator? So you shouldn't see a big difference between a chevette heatercore and one w/ 13 more square inches (multiplied by 2" for the depth)?

If the small one can displace the heat you are throwing at it, there would be no difference. The question you would have to determine is how many Watts the radiator can effectively move away. I have a small Senfu radiator. It allows me to have some great temperatures and its just a little small thing. BrianW is using a gargantuan rad. I don't understand how the temps could be much better, but no once corrected him during his post of his magnificently crafted dual rad. However with the variables of air to the rad, and use of fans its a loaded question.

Rad does make a difference, it depends if you water cool CPU only or cool Cpu, NB, SB, Video card, etc.
Then you will need a bigger Rad or Dual ones.

Im just cooling my CPU so a 6x6x2 from D-Tek will do me fine.
I could probably split the line from rad and cool Cpu and something else (video card).

Right now using a Vantec all Copper kit on NB(NorthBridge) and that works fine for me.