Estimating heat output - 5850

[amazingrando]

Hi everyone!

Does anyone have a good idea of how many BTU's a 5850 puts out at full load?  Trying to estimate how much airflow I need for my rigs.

Thanks

[chungenhung]

assuming the card uses 200W.
one hr of 200w will produce 682 BTU per hour
http://www.mhi-inc.com/Converter/Energy%20Converter.htm

[SgtSpike]

A 5850 only uses about 150w.

[amazingrando]

Kind of a stupid question, but if the GPU uses 150W, is all of it dissipated as heat?

[SgtSpike]

Kind of a stupid question, but if the GPU uses 150W, is all of it dissipated as heat?

Yes.  All wattage eventually turns into heat.  Even fans blowing air... the air creates friction until it slows to a stop, and all of that friction turns into heat.  Same with light - as it is absorbed by the various surfaces it touches, it turns into heat.  The reflected light is what we see, but it all keeps bouncing around until it is all absorbed.  But the majority of wattage in a computer is used by transistors switching, which creates heat as well.

[amazingrando]

Thanks SgtSpike!

[Kermee]

CPUs, GPUs, uC's, and most other semiconductors are less than 1% efficient.

So yes, basically 100% of TDP comes off as heat.

Cheers,
Daniel

[mike678]

A 5850 only uses about 150w.

Overclocked 5850's generate more than this My rig is set up for 920/325 and its 5 cards. According to my kw reader its about 1kw so closer to 170w per card.

[SgtSpike]

CPUs, GPUs, uC's, and most other semiconductors are less than 1% efficient.

So yes, basically 100% of TDP comes off as heat.

Cheers,
Daniel

Do transistors actually move?  I'm not familiar enough with how they work to know the answer...

A 5850 only uses about 150w.

Overclocked 5850's generate more than this My rig is set up for 920/325 and its 5 cards. According to my kw reader its about 1kw so closer to 170w per card.

This is true.  I am assuming a stock card when I say 150w, and even then, that's not really an exactly accurate number.

[mike678]

This is true.  I am assuming a stock card when I say 150w, and even then, that's not really an exactly accurate number.

Yes I agree that's an estimate on my part but I have a semperon so 150w for mobo/ram/cpu/hd is a pretty safe bet.

[SgtSpike]

This is true.  I am assuming a stock card when I say 150w, and even then, that's not really an exactly accurate number.

Yes I agree that's an estimate on my part but I have a semperon so 150w for mobo/ram/cpu/hd is a pretty safe bet.

More like 50w if your sempron is just idling while mining...

Total, 200w would be my guess.

Then again, it also depends how efficient your PSU is... add 20% or more to those figures for the heat loss from the transformers in the PSU.

[Kermee]

Do transistors actually move?  I'm not familiar enough with how they work to know the answer...

In a sense, the physical 'gates' do for the switching. =)

Cheers,
Kermee

[mike678]

More like 50w if your sempron is just idling while mining...

Total, 200w would be my guess.

Then again, it also depends how efficient your PSU is... add 20% or more to those figures for the heat loss from the transformers in the PSU.

I'll just post exact specs.

MSI 890FXA-GD70
corsair 1200watt gold series
5xsapphire hd 5850
2x1gb ram
this hd (http://www.newegg.com/Product/Product.aspx?Item=N82E16822136770&Tpk=22-136-770)
Sempron 130

At 920/325 I get around 1kw. I'm too lazy to find exact numbers feel free to figure it out if you want.

[amazingrando]

I'll just post exact specs.

MSI 890FXA-GD70
corsair 1200watt gold series
sapphire hd 5850
2x1gb ram
this hd (http://www.newegg.com/Product/Product.aspx?Item=N82E16822136770&Tpk=22-136-770)
Sempron 130

At 920/325 I get around 1kw. I'm too lazy to find exact numbers feel free to figure it out if you want.

With how many GPUs?

[SgtSpike]

Catfish, that was a far lengthier reply than I was requesting - a simple "no" would have sufficed.    That said, thanks for writing all of that!  Makes sense that transistors simply increase resistance to force the electricity to another path though.  No physical movement involved.  So, if that's the case, then Kermee is wrong - it's not "basically" 100% of electricity is direct heat loss - it IS 100% electricity is direct heat loss.  Unless you happen to have glowing-hot semiconductors, which, probably won't last long anyway. 

More like 50w if your sempron is just idling while mining...

Total, 200w would be my guess.

Then again, it also depends how efficient your PSU is... add 20% or more to those figures for the heat loss from the transformers in the PSU.

I'll just post exact specs.

MSI 890FXA-GD70
corsair 1200watt gold series
sapphire hd 5850
2x1gb ram
this hd (http://www.newegg.com/Product/Product.aspx?Item=N82E16822136770&Tpk=22-136-770)
Sempron 130

At 920/325 I get around 1kw. I'm too lazy to find exact numbers feel free to figure it out if you want.

That system cannot possibly be drawing 1kw of power, unless you have multiple GPU's.  I calculate it would use about 230w, PSU efficiency included.

[scifimike12]

Don't forget that the cooler your card is, the same will be for your room.

I have my 5870's mining continuously in my basement, both barely hit 40°C on a hot day.  But if I were to add a few MSI 5770 Hawks' @ 85% fan speed, my basement begins to warm up a bit, and so do my cards.

I tried setting up a simple build in my room and couldn't bare the heat after a few nights.  97°F inside, while it's 71°F outside just ain't right. 

[haploid23]

A 5850 only uses about 150w.

Overclocked 5850's generate more than this My rig is set up for 920/325 and its 5 cards. According to my kw reader its about 1kw so closer to 170w per card.

it actually generates less. 5850's TDP is 150w, that means it's designed to dissipate 150w of heat. the actual usage, even at 100% load, will draw less than 150w. overclocking the core (however underclocking the memory) might put you close to the TDP, but it shouldn't go over unless there's heavy overvolting.

and also note that AC and DC power are a little different. the rated 150w TDP is based on DC pulled from the PSU, when you read 1000w your meter, that's AC power, which is pulled from the wall. in this case, you need to take into account the PSU efficiency before claiming it's 170w of real DC power draw

[mike678]

That system cannot possibly be drawing 1kw of power, unless you have multiple GPU's.  I calculate it would use about 230w, PSU efficiency included.

I updated the post there's 5 5850's I mentioned it a little earlier in the thread and I assumed it was known already. Plus I wrote that when I was drunk lol

it actually generates less. 5850's TDP is 150w, that means it's designed to dissipate 150w of heat. the actual usage, even at 100% load, will draw less than 150w. overclocking the core (however underclocking the memory) might put you close to the TDP, but it shouldn't go over unless there's heavy overvolting.

and also note that AC and DC power are a little different. the rated 150w TDP is based on DC pulled from the PSU, when you read 1000w your meter, that's AC power, which is pulled from the wall. in this case, you need to take into account the PSU efficiency before claiming it's 170w of real DC power draw

I have a CORSAIR Professional Series Gold AX1200 (http://www.newegg.com/Product/Product.aspx?Item=N82E16817139014)

How would I go about calculating watts used by each card then?

[bcforum]

CPUs, GPUs, uC's, and most other semiconductors are less than 1% efficient.

So yes, basically 100% of TDP comes off as heat.

Cheers,
Daniel

I'm puzzled by your comment. What actual work is being performed by the 1% here? Even the air that is moved isn't being stored at a higher pressure, so after you run your 1KW rig for 1 hour you have increased the heat in your room exactly the same as a 1KW heater.

[Kermee]

I'm puzzled by your comment. What actual work is being performed by the 1% here?

Transistor gating/switching for the 2.15 billion transistors in a 5850.  There is 'work' being done still.

Like I said... it's less than 1%.  You cannot apply 'high school' level of physics in entropy with semiconductors.

It 'work' efficiency wasn't an issue, then we wouldn't need to continue to shrink dies sizes.

Cheers,
Kermee