Convection in Water Cooling

[Fibbles]

An aquaintence of mine (fellow clan member) is thinking of buying a Black Ice Xtreme, tubing, and a waterblock of some sort for a 1/2" system (I suppose). He wants to put a low speed and perhaps silent fan on the rad. The other thing is, since he wants this to be totally silent, he thinks that he'll be able to run without a pump. I'm not sure what his reasoning is, but is that possible at all? He certainly seems to think so. For my convection system, I'd just replace the active rad with the passive rad, but what would I do by not running a pump, besides overheating my CPU?

:confused:

[fivecheebs]

Sounds crazy to me!

[Da_Rude_Baboon]

From reading the 'challenge' thread it looks like you need a decent flow through the rad for it to cool efficently. If your relying on convection your not going to get the water to move rapidly enough through the rad for decent cooling to take place. I beleive he would end up with, and i use the technical term, a kettle. :lol:

[Knipex]

From reading the 'challenge' thread it looks like you need a decent flow through the rad for it to cool efficently. If your relying on convection your not going to get the water to move rapidly enough through the rad for decent cooling to take place. I beleive he would end up with, and i use the technical term, a kettle. :lol:
Spot on.

[Fibbles]

This is what he asked me: "So, do you think a BIX with a low speed fan can cool a 6800 GT with no pump?" When I said that I didn't think so, this was his response: "Not air convection. I understand that convective cooling (i.e. using air convection) requires a different rad design to be effective. However there is convection in the water as well. I'm organizing, so I'll pull out an old fluid dynamics text and see if it's still called convection in water."

[Darv]

There is convection in water. The hot water will rise but it will be so slow that the graphics card will probably have melted before the water does one loop.

We don't use pumps for fun. They're there for a reason :p

[Fibbles]

There is convection in water. The hot water will rise but it will be so slow that the graphics card will probably have melted before the water does one loop.

We don't use pumps for fun. They're there for a reason :p
Yeah, I know that, and of course you know it, but some people are sure they know more and once set in the wrong pathway, they become forever dislodged and drag others down with them.

**I got that from another cooling site. ^_^

[Da_Rude_Baboon]

lol Fibbles between your guy with his SATA problems and the convection cooler your not having much luck with aquaintences at the moment! :P

[Starbuck3733T]

lol :blink: :wacko:

[BillA]

Dr.Fibbles

you might wish to refer your friend to an excellent article by LegumaN (Antoine Dechaume)
http://leguman.ht.st/
BASIC PRINCIPLES INVOLVED IN HEAT TRANSFER AND COOLING RELATED TO PROCESSORS

[Fibbles]

lol Fibbles between your guy with his SATA problems and the convection cooler your not having much luck with aquaintences at the moment! :PI know, everyone would rather pretend they know something and then when they "play along" to real help, but not know what they are doing, nevermind.

Dr.Fibbles

you might wish to refer your friend to an excellent article by LegumaN (Antoine Dechaume)
http://leguman.ht.st/
BASIC PRINCIPLES INVOLVED IN HEAT TRANSFER AND COOLING RELATED TO PROCESSORSDone.

[Fibbles]

Latest response (after I said it would basically create a kettle):

No, no, no.

1) There will be convective water current in unforced systems (i.e. pumpless).

2) The processor goes through heat death before it reaches 100C.

3) The GFX card may as well, I don't know which card you have.

4) Much of the heat generated by the cpu (3-10%, I dunno) will escape along the pins into the mobo, or out the sides of the block, or ... you get the idea.

5) The boiling point of water is dependent on the pressure of the environment. As your watercooling is a closed loop, with a small amount of air, water will likely be boiling above 100C, a temperature your water will never reach.

Now, it is entirely possible that since
a) Convective flow will be minimal,
b) water has a relatively high specific heat
c) the performance of a radiator is highly dependent on the waterflow through said radiator.
d) stuff,
that your computer would fry/trip thermal protection if you were operating in a pumpless loop.

I've been thinking about this, and though I will certainly get the dtek pumps if I go watercooling, I am intrigued by the passive cooling. One of the things I can think of is that you of course need an open flow designed block and radiator. I.e. one of those shitty ass tube/fin radiators, and a maze block or maybe an old swifty, not an impingement block of any kind. Then, you might be able to cool a gpu alone.

Quick back of the napkin calculations give me somewhere around absolute max of 75 watts of heat dissipation from the GPU (110 watts maximum power draw, 15% efficiency, 80% consumed by GPU itself). This is definitely worst case, because (a) the max draw is for a 6800U, and (b) I'm betting at least another 5 watts go off the back of the card on that big piece of metal.

But, assuming that's the total energy that needs to be dissipated (spelling), I think it's reasonable to assume that it can be done unforced. hmmmm, dunno, gonna think about this soon as I have some time, and remember, i.e. never.