Wht do GPUs use SOooo Much Power??

MrChooks · 07-09-2008, 06:48 PM

Just a curiosity question - and I admit to having virtually no knowledge on 'puters

- BUT from all I have read in TSF postings - it seems to me that GPUs have a voracious demand for power - especially the higher end products.

Given that all the other "blitz 'n pieces" inside a computer seem to have quite modest power demands - can someone explain to me - (in very simple terms - coz I know very little about computer gutz) - where does all the power go inside these GPUs and what goes on inside them to make them demand so much power. :

This is not urgent - 'tiz just to satisfy my curiosity

**magnethead** · 07-09-2008, 08:52 PM

actually, CPU's and GPU's both pull ALOT of power. the GPU just pulls a bunch more. Just as the PCI-E GPU uses a 6 plug power plug, the CPU uses that 4 pin plug that's usually by it for direct power.

a CPU/GPU is really just a bunch of switching transistors for the most part. The operating frequency is simply how many 'switches' the GPU/CPU can perform per second.

a GPU core operating at 1100 MHz is pulling 1,100,000 state-switchings (either open or closed) per second. and every time a transistor changes, it's assigned binary bit changes too.

On older analog displays, switching speed didnt matter because of the refresh rate of the monitor- 60Hz (or 75 or 85, picked by user), on a 480 line screen.

Now with digital displays, we're pulling 1,310,720 pixels (1280x1024) and higher. At true color, that's 32 bits per pixel. That's 41,943,040 bits to make up a 1280x1024 display.

That's my loose interpretation of it from what i learned collectively in computer maintenance and science. Maybe somebody can answer it better.

MrChooks · 07-09-2008, 11:22 PM

Magnethead - I really appreciate your reply and inputs - but being an electronics klutz - I am still in a daze. Where does all that power disappear to?? What consumes so much power??

I recall (dimly) my ocean yacht racing crewing days - back when boat comms were thru SSB (HF). We had a 100w SSB (HF) X'civer. This mother (all solid state) had an Xmit current draw of over 35A (@12 V) - albeit it could Xmit over 1000 NM - it amazed me that the power supply cable was "starter motor battery supply cable" although I found out quickly that one does not a/ Touch the Xmitter heat sinks at the rear of the radio or /b the 14 foot whip aerial if the mic was live and transmitting - both made your eyes roll big time

**magnethead** · 07-10-2008, 01:01 AM

Quote:

Originally Posted by MrChooks

Magnethead - I really appreciate your reply and inputs - but being an electronics klutz - I am still in a daze. Where does all that power disappear to?? What consumes so much power??

I recall (dimly) my ocean yacht racing crewing days - back when boat comms were thru SSB (HF). We had a 100w SSB (HF) X'civer. This mother (all solid state) had an Xmit current draw of over 35A (@12 V) - albeit it could Xmit over 1000 NM - it amazed me that the power supply cable was "starter motor battery supply cable" although I found out quickly that one does not a/ Touch the Xmitter heat sinks at the rear of the radio or /b the 14 foot whip aerial if the mic was live and transmitting - both made your eyes roll big time

I'd say an easy 70% is likely lost to heat.

The other 30% powers the transistors.

MrChooks · 07-10-2008, 01:05 AM

Hey Magnethead - a quick digression - wot happened to that wiz bang case you were building back last April / May??? -

All has gone quiet - and it was looking cute - so how'z bout some pics of the finished job (but only after you have finished taking me thru TSF "electronics 101"!!

) This will be good - as an old mining engineer - I am used to power consumption in megawatts - not micro watts - hence my problems in understanding all the little bitty electronic things

MrChooks · 07-10-2008, 01:11 AM

Quote:

Originally Posted by magnethead

I'd say an easy 70% is likely lost to heat.

The other 30% powers the transistors.

So itz only a metter of time before some enterprising chip or MB builder puts a coffee maker on one of these things - soundz good to me - sign me up!!

**magnethead** · 07-10-2008, 09:47 AM

Quote:

Originally Posted by MrChooks

So itz only a metter of time before some enterprising chip or MB builder puts a coffee maker on one of these things - soundz good to me - sign me up!!

lol.

You talking about the wooden case with the 3 big fans? I don't have the finished pics on my website yet (eventually I'll get to that).

I'm sure once they figure out how to make GPU's at 55 or 45nm architechure like they do CPU's, more of the power will go to processing and less to heat I'm sure. Although my knowledge about stops there. You have to take notice- most G70 GPU's run in the 50-60C idle range, while most properly cooled CPU's are in the 30-40C range. I don't have a good call number on the new G90's in the 9600's, but i think i saw they idle in 55-65C range, but they also have those huge, massive heatsinks on them that take up every bit of 2 slots, the full length of the card.

Project Log: Hybrid Twist

lets see your rig

MrChooks · 07-10-2008, 03:11 PM

Looking forward to the pic of the finished "project hybrid twist" with optional "toast & coffee maker" - seems a shames to let all that GPU board heat disappear into the ether!!

**magnethead** · 07-10-2008, 07:39 PM

Quote:

Originally Posted by MrChooks

Looking forward to the pic of the finished "project hybrid twist" with optional "toast & coffee maker" - seems a shames to let all that GPU board heat disappear into the ether!!

lol.

HT is pretty much finished. Still not 100% sure what i want to do with it, right now I'm looking at web/file server but hard to say. It really needs to be about 2 inches taller for the Cd drive door to clear like it should. Right now it has a generic 600 watt cheapo LEd power supply with a pentium 2 350 MHz, 256 RAM, and win 2K. With a PCI 5200 gfx card or something liek that.

MrChooks · 07-10-2008, 08:56 PM

Well if you are going to add a couple inches - that would be ideal time to make allowance for the toast & coffee maker lol - will keep your sustenance up whilst you wait fro DVDs to burn with a light-scribe label

07-09-2008, 06:48 PM	#1 (permalink)
MrChooks Gearhead Join Date: Apr 2008 Location: Sydney, Australia Posts: 613 OS: Windows XP Home SP 3 My System	Wht do GPUs use SOooo Much Power?? Just a curiosity question - and I admit to having virtually no knowledge on 'puters - BUT from all I have read in TSF postings - it seems to me that GPUs have a voracious demand for power - especially the higher end products. Given that all the other "blitz 'n pieces" inside a computer seem to have quite modest power demands - can someone explain to me - (in very simple terms - coz I know very little about computer gutz) - where does all the power go inside these GPUs and what goes on inside them to make them demand so much power. : This is not urgent - 'tiz just to satisfy my curiosity

07-09-2008, 08:52 PM	#2 (permalink)
magnethead Registered User Join Date: Mar 2006 Location: Texas, USA Posts: 3,570 OS: Vista ultimate 32bit My System Blog Entries: 3	Re: Wht do GPUs use SOooo Much Power?? actually, CPU's and GPU's both pull ALOT of power. the GPU just pulls a bunch more. Just as the PCI-E GPU uses a 6 plug power plug, the CPU uses that 4 pin plug that's usually by it for direct power. a CPU/GPU is really just a bunch of switching transistors for the most part. The operating frequency is simply how many 'switches' the GPU/CPU can perform per second. a GPU core operating at 1100 MHz is pulling 1,100,000 state-switchings (either open or closed) per second. and every time a transistor changes, it's assigned binary bit changes too. On older analog displays, switching speed didnt matter because of the refresh rate of the monitor- 60Hz (or 75 or 85, picked by user), on a 480 line screen. Now with digital displays, we're pulling 1,310,720 pixels (1280x1024) and higher. At true color, that's 32 bits per pixel. That's 41,943,040 bits to make up a 1280x1024 display. That's my loose interpretation of it from what i learned collectively in computer maintenance and science. Maybe somebody can answer it better. __________________ For proper support: what are you running? graphics, cpu, m/board, ram, PSU brand wattage PCI-E requires 26 amps at 12 volts. That's a 650W PSU. Power Supply Info and Selection . Info on thermal compounds & application . TEST PSU USING MULTI-METER . Bench Testing Your System

07-09-2008, 11:22 PM	#3 (permalink)
MrChooks Gearhead Join Date: Apr 2008 Location: Sydney, Australia Posts: 613 OS: Windows XP Home SP 3 My System	Re: Wht do GPUs use SOooo Much Power?? Magnethead - I really appreciate your reply and inputs - but being an electronics klutz - I am still in a daze. Where does all that power disappear to?? What consumes so much power?? I recall (dimly) my ocean yacht racing crewing days - back when boat comms were thru SSB (HF). We had a 100w SSB (HF) X'civer. This mother (all solid state) had an Xmit current draw of over 35A (@12 V) - albeit it could Xmit over 1000 NM - it amazed me that the power supply cable was "starter motor battery supply cable" although I found out quickly that one does not a/ Touch the Xmitter heat sinks at the rear of the radio or /b the 14 foot whip aerial if the mic was live and transmitting - both made your eyes roll big time

07-10-2008, 01:05 AM	#5 (permalink)
MrChooks Gearhead Join Date: Apr 2008 Location: Sydney, Australia Posts: 613 OS: Windows XP Home SP 3 My System	Re: Wht do GPUs use SOooo Much Power?? Hey Magnethead - a quick digression - wot happened to that wiz bang case you were building back last April / May??? - All has gone quiet - and it was looking cute - so how'z bout some pics of the finished job (but only after you have finished taking me thru TSF "electronics 101"!!) This will be good - as an old mining engineer - I am used to power consumption in megawatts - not micro watts - hence my problems in understanding all the little bitty electronic things

07-10-2008, 03:11 PM	#8 (permalink)
MrChooks Gearhead Join Date: Apr 2008 Location: Sydney, Australia Posts: 613 OS: Windows XP Home SP 3 My System	Re: Wht do GPUs use SOooo Much Power?? Looking forward to the pic of the finished "project hybrid twist" with optional "toast & coffee maker" - seems a shames to let all that GPU board heat disappear into the ether!!

07-10-2008, 08:56 PM	#10 (permalink)
MrChooks Gearhead Join Date: Apr 2008 Location: Sydney, Australia Posts: 613 OS: Windows XP Home SP 3 My System	Re: Wht do GPUs use SOooo Much Power?? Well if you are going to add a couple inches - that would be ideal time to make allowance for the toast & coffee maker lol - will keep your sustenance up whilst you wait fro DVDs to burn with a light-scribe label