what would adding extra items do to the temps exactly?

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diesel
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what would adding extra items do to the temps exactly?

Post by diesel » Wed Mar 29, 2006 2:47 am

hi i've got a resevator and its keeping my cpu at about 50C under a full load.

this is ok for me as i understand 60C is the limit of acceptable.

now since converting to water cooling i've been checking my temps and found that my HDD is getting to 70C which is a little alarming, and my northbridge is going to mid 40's.

now i'm getting a silentstar single after reading up on the double version. this should help keep the tempsdown on the HDD, and i'm thinking of adding a northbridge cooler as well.

my question are these, what will the extra cooling demands do to the other temps?

will it pump so much heat into the system that the cpu will hit temps high enough to cause consern?

if so would fitting another radiator help or would the it be too much for the pump?

jamesavery22
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Post by jamesavery22 » Wed Mar 29, 2006 5:33 am

HDs do not consume that much power. <22watts even for the fastest 15k drives. People tend to worry about their drives getting hot a little more than they need to. Their MTBF takes semi-crappy environments into account.

watercooling a HD is overkill. most desktop HDs dont even need airflow.

but to answer your question anyways,
to get relative temps compare 20watts to whatever you have in the loop already.
SPCR said the reserator has about 0.39 C/W.

So (CPU temp) = (Ambient temp) + (C/W) * (CPU power dissapation)

Think of the "CPU" as a system. So instead of just having the CPU, you now have the CPU+HD. The "System" temp is a between the two. I don't know how to calculate the individual C/W but this will give you an idea.

Adding the HD blocks will also drop the C/W since the flow will be reduced due to restriction.

diesel
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Post by diesel » Wed Mar 29, 2006 6:08 am

ok so if im to work this out i'm looking at a formula like this?

So (CPU temp) = (Ambient temp) + (C/W) * (CPU power dissapation + vga dissipation + HDD power disapation)

so assuming my ambient temp is 20 to work out my cpu + vga's power dissipation i'll need to do this

cpu temp/ (ambint temp + c/w)

which is atm after a heavy game playing time

54/ (20 + 0.39) = 2.75

so i just need to work out the dissipation of the HDD and add it to that figure and do your original formula right?

ok any idea where i can find out what the dissipation on my HDD is?

jamesavery22
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Post by jamesavery22 » Wed Mar 29, 2006 6:49 am

Sorry, I dont follow your math.

It should be this.

(CPU temp/VGA temp avg) = (Ambient temp) + (C/W) * (CPU power dissapation + VGA dissipation)

You can't go backwards unless you calculate the individual C/W for each of your CPU and VGA.

If you need to get a guesstimate of what each individual temp is you need to get the C/W of each part in the loop.

So the C/W from the air to the coolant(via the radiator) and the C/W rom the coolant to the chip(via whatever block).

That 0.39 C/W is for the entire reserator system (just the CPU so yours that has CPU and VGA would be higher). As in the C/W from air to chip.

I don't know of any review or anyone on a forum that has done those measurements and calculations.

There are a lot of variables you are leaving out though. Namely flow.

diesel
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Post by diesel » Wed Mar 29, 2006 7:43 am

right

looking at what i've found so far it shouldnt put the temps up by too much.

if it does i'll look at my options after wards.

Butcher
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Post by Butcher » Wed Mar 29, 2006 8:55 am

Main problem is likely to be reduction of flow from adding extra blocks. That will have far more impact than any additional heat load introduced.

Also 70C is too hot for a HDD - most are only specced to 60C operating temp...

MikeC
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Post by MikeC » Wed Mar 29, 2006 9:14 am

Even a tiny bit of airflow from a very quiet fan would drop the HDD temp to probably 40C or better, assuming there is a reasonably open intake and matching exhaust vent. If my HDD was at 70C... :shock:...I'd do this NOW!
Mike Chin, SPCR Editor/Publisher
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jamesavery22
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Post by jamesavery22 » Wed Mar 29, 2006 9:45 am

Oh yeah... the most common problem with temp probes is they aren't read correctly. Wouldnt be surprised if 70c was way off what the HD temp really is. Put your hand on the drive. If it isnt uncomfortable then its fine.

Butcher
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Post by Butcher » Wed Mar 29, 2006 12:23 pm

You massively shorten the life of the drive by running it hot. If *any* piece of the drive is even close to 70C it's way too hot.

diesel
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Post by diesel » Thu Mar 30, 2006 8:18 am

hmm wasnt expecting this, but my cpu has actually gone down!

i got the HDD and northbridge cooler today and fitted them then decided to test them out with some game play.

been running for a while now and im getting 48C on my CPU, 41C on mt northbridge, and my HDD has dropped down to about 61C, not as big a drop as i was hopping, maybe its just this model HDD runs hot (if anyones interested its a maxtor 6Y060L0) other than that nothing more to add.

i might put another rad in to cool it down further at a later date.

thetoad30
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Post by thetoad30 » Thu Mar 30, 2006 8:39 am

Butcher wrote:You massively shorten the life of the drive by running it hot. If *any* piece of the drive is even close to 70C it's way too hot.
Normally, I would totally agree with you.

However, I have seen temps on the chips of the drive reach this hot while the drive thermal probe was reporting a decent (around 45-55C) temps.

I personally would never let my hard drive get anywhere above 55C without actually trying to figure out why there was so much heat being produced.

I've had lots of bad luck with hard drives lately.

On to your question:

I'm a new water cooling person too, and from what I've read, a Northbridge waterblock does NOTHING to your system except cause a decrease in water flow. For such a low-flow pump that the reserator has, I would actually consider removing this from the loop and trying it that way.

Northbridge temps can go pretty high. I've actually seen mine hit 70C on the heatsink measured with an external probe. This was when I was massively overclocking (well, massive for air cooling I guess ;) ).

As for the hard drive, remember that when you water cool, it STILL needs fans to remove heat from the rest of the components in the case. You can't just throw away all your fans.

MikeC is right about airflow. I have a Tricool from the P180 (the 25mm version) in the chamber instead of the 38mm. It's on low, around 20 CFM via the article. I have 4 hard drives in that lower chamber. Most don't get above 35-40C, and rarely, if ever, get to 55C (only when doing a massive restore pumping 50+ gigs of data).

Just a few ideas.

Butcher
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Post by Butcher » Thu Mar 30, 2006 9:35 am

Noticed my Atlas 15K II was getting a bit warm last night (I recently moved it from the main drive cage to being suspended in the 5.25" bays). Putting a spare 80mm fan blowing over it seems to have massively reduced the temps and the fan is inaudible over the rest of my stuff (it's a yate loon fan and very quiet anyway).

Sendorm
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Post by Sendorm » Fri Apr 14, 2006 5:35 am

i dont think your harddisk is working at 70C. You'll feel the heat of something at that temperature without even touching.

I guess there is something wrong with your temp sensor on the harddisk.
Try using your hands and touch the metal over the harddisk. If it feels hot, it is higher than 40C. If you cant stand the temp, it is probably higher than 55.

Now about water cooling a harddisk:
It is totally overkill for the temp benefit, yeah. But what about the silence?
You wont hear a low speed fan blowing over the harddisks. But you'll still hear the hardisk. So use something to watercool the harddisk and wrap the total thing as thick as you want until no sound is perceptible.

Typically you'll get 20C above ambient, in a good watercooled system for 100watts. So adding a 10watts harddisk to that loop will increase the temps by 2 degrees. Nothing important.

Butcher
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Post by Butcher » Fri Apr 14, 2006 12:55 pm

Sendorm wrote:Typically you'll get 20C above ambient, in a good watercooled system for 100watts. So adding a 10watts harddisk to that loop will increase the temps by 2 degrees. Nothing important.
How do you figure that? Most of the delta for CPU to ambient is in the TIM and waterblock interfaces, not the radiator interface. A typical water system has the water only a few degrees above ambient. Adding 10W to the water will have negligable impact on the temps of your CPU, unless the flow restriction caused by the extra block causes your CPU block to perform markedly less well.

Sendorm
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Post by Sendorm » Fri Apr 14, 2006 1:34 pm

hmm thinking...

In my water system, ambient is 22-24 degrees. And during load I get about 30-32C water temps. And this is with a amd 3000+ venice which outputs much less than 100watts (around 50-60watts I guess).

So 20C is not really off base for a 100watt system. If you have a good contact between the IHS and the cpu core, the cpu temp you'll read will be nearly as same as the water temp. That's why people remove their IHSes.

Of course my "typical system" does not contain a 3 * 12cm radiator :)

Butcher
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Post by Butcher » Sat Apr 15, 2006 2:14 am

Sendorm wrote:hmm thinking...

In my water system, ambient is 22-24 degrees. And during load I get about 30-32C water temps. And this is with a amd 3000+ venice which outputs much less than 100watts (around 50-60watts I guess).

So 20C is not really off base for a 100watt system. If you have a good contact between the IHS and the cpu core, the cpu temp you'll read will be nearly as same as the water temp. That's why people remove their IHSes.

Of course my "typical system" does not contain a 3 * 12cm radiator :)
Don't forget pump heat.

Also, radiators are not linear with additional heat load - the hotter the water the more efficient the heat transfer to the air due to the higher temperature gradient. I've dropped ~400W (from TECs) through my rad without getting higher than a 20C water-air delta before and it's not even a 3x120mm.

Even if you have good contact between IHS and core you'll still have a large delta. It's almost impossible to eliminate that as the bottleneck with commonly available materials.

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