General musings calculating power consumption

[MaxBurn]

A little while ago I smoked a Seasonic S12-430 by adding a second video card to do SLI, previously I had been running for about eight months with that system with the one video card so I think it was pretty clear what killed it. I upgraded the power supply to a S12-550 which worked for that, but I found out that SLI is a major PITA due to nvidia politics and spent a lot of money to rebuild my game PC. Now I am pondering if I will be in the same power situation if I do crossfire with this system, seems strange that these huge power supplies are needed but I guess sometimes they are.


Motherboard components and USB devices (not a lot of those)
probably less than 50w?

x1950xtx
probably about 126w
worst case possible 75w from motherboard and 75w from the PCIE power cord = 150w total.

CPU E6600
Thermal Design Power 65w about 75w with an overclock and no volt tweaks?

wd740gd
Power Dissipation
Read/Write 8.40 Watts
Idle 7.90 Watts
Standby 1.76 Watts
Sleep 1.11 Watts

Seagate 160g drive
just doubling the raptor for now.

Fans Antec Tricool 120mm
High 0.24A (max.) 2.88 W
Medium 0.2A 2.4 W x5 = 12.5w
Low 0.13A 1.56 W


274 watts total now.
126 second card
----------------------
400 total worst case.


Old system same as above only with a AMD 3700+ and SLI 7800GT. This ran for a long time but after one week in SLI I smoked a Seasonic S12-430:
319w total power with SLI.




Other stuff, gathered various sources:

Previous video cards:
7800GT 75-80 W
Dual 7800GT in SLI: 112 watts MAX
Geforce 7800GT = 39 watts @ idle / 56 watts @ peak load
Geforce 7800GT 73 watts


previous CPU
AMD 3700+ (1core San Diego) 89 Watts TDP

Similar to the x1950xtx (GDDR3 draws a little more power)
Radeon X1900XTX = 49 watts @ idle / 120 watts @ peak load
Radeon X1900XTX 135 watts

 

[mubs]

Initial power draw (inrush?) will always be higher than steady state. These significantly higher loads, though much shorter in duration, could be deadly to power equipment.

 

[MaxBurn]

Good point.

I forgot to mention that when my seasonic died it was in the middle of a game though. It straight up turned off then I got about three more boots out of it with subsequent crashing before it simply would not turn on again.

 

[CougTek]

I have the following system :

• Intel Core 2 Duo E6400
  GigaByte GA-965-DS3
  2GB OCZ DDR2 800MHz in dual channel
  a smallish 20GB hard drive I had left over
  16X LG DVD-RW
  Sapphire Radeon XT 256MB PCI-E

All powered by a relatively modest Seasonic S12-380HB power supply. The system is currently running the folding@home SMP client so the CPU is busy at 100%. I used to run the GPU FAH client on it too (but not at the same time as the SMP client since it cannot be done AFAIK). This system has been operating for months without issue.

I've had a second hard drive into it for a few weeks too.

 

[MaxBurn]

Thats fairly close to me except for the video card maybe, which one is that? My motherboard is the Gigabyte GA-965P-DQ6 so we are pretty close there too.

How was the weather up there today, was actually a little hot down here in NH just south of you.

 

[CougTek]

Thats fairly close to me except for the video card maybe, which one is that?

http://www.sapphiretech.com/ca/products/products_overview.php?gpid=169&grp=3

My system always operates with an ambiant temperature of 22-23C.

 

[LiamC]

My system always operates with an ambiant temperature of 22-23C.

yeah, but isn't the ambient of Can-uh-duh about -20C?

:twistd:

 

[CougTek]

Maybe, but I don't live in Can-uh-duh. I live in Québec.

And our climate is quite humid so we tend to run our computer inside our houses here. Inside mine, it is ~22-23C (except when I open the windows in winter where it drops to ~5-10C).

 

[Clocker]

I ran 2x 7800GT in SLI for a while on an NF4 (power hungry IIRC) motherboard with an Antec SP-500 PSU w/o problem. That was with a 4400+ CPU, 2GB of RAM and three SATA HDDS. A single X1900XTX worked fine is well.

 

[time]

A quick Google revealed this, which sounds about right.

 

[MaxBurn]

Hmm, I have a fluke and an amp clamp somewhere so I think I might have to shred a power cable to satisfy some curiosity. Should be interesting.

So if I measure something on that AC cable and my power supply is rated at 80% efficiency that means I subtract 20% of my reading to get the watts dissipated my computer right?

What that won't tell me is what I am pulling on the individual rails though. What I might have done is just overload one 12v rail and the others were unloaded. Too bad they don't label which cable coming out of the power supply goes to which 12v rail.

 

[Adcadet]

I thought Silent PC Review has some info up that showed that most systems require far less power than the max. I seem to remember them ignoring the whole "start up power suck" thing - you know, the reason the lights dim when large machines turn on. What is that, reverse current or something? I forget what that's called but I thought it was really cool back when I took physics....7 years ago. Damn I'm old.

 

[MaxBurn]

Inrush is when you close a breaker to energize a transformer, can be up to a thousand times what the transformer is rated but only for a very small instant of time. Really a non issue in PC's as they simply don't have transformers.

Startup current would more refer to a motor starting like fans and hard drives. I kind of think this is minimal.

 

[ddrueding]

IIRC, the only additional load for a computer is spinning the drives up. 4x running load (20W vs. 5W) is what I remember hearing.

My system (see sig) never posts from a cold start (video fails to initialize). All I need to do is power it on, count to 5 (so the drives spin up), then hit the reset button. It would be annoying, but I've only done it 3 times - ever.

 

[Adcadet]

Do your drives have a jumper to delay spin-up? Probably harder to move the jumper than just hit the reset button.

 

[ddrueding]

Nu jumper (just standard SATA drives) but I hope the 3Ware controller I'm about to hook them up to supports staggered spin-up, then I won't have to get a 1kW PS.

 

[LunarMist]

I forget what that's called but I thought it was really cool back when I took physics....7 years ago. Damn I'm old.

Oh please. I remember most of the EE from 70s classes.

 

[LiamC]

Maybe, but I don't live in Can-uh-duh. I live in Québec.

Damn Francophiles have staged a coup d'État.

Seriously, do the Québecois not consider themselves part of Canada? I know there have been some separatist moves, but is the aim a full-blown succession? And if so, why–what would it bring for those with French ancestry?

Edit: Maybe this deserves it's own thread, as it seriously derails this one...

 

[time]

My system (see sig) never posts from a cold start (video fails to initialize).

Just get rid of the NEO. There's nothing in your sig that indicates a monstrous load.

 

[Bozo]

Nu jumper (just standard SATA drives) but I hope the 3Ware controller I'm about to hook them up to supports staggered spin-up, then I won't have to get a 1kW PS.

The BIOS might offer a delayed hard drive spin-up time setting. Intel boards do.
Don't remember seeing a delay setting on a 3Ware though.

Bozo :joker:

 

[MaxBurn]

I don't see a delayed spin up available on my aging 3ware 7500-8.

 

[Mercutio]

On the subject of FreeNAS, why not set it up in a Virtual Machine if you just want to see how it works? VMware server is free and easy to use, guys.

Seriously, do the Québecois not consider themselves part of Canada?

Coug certainly doesn't.

I've heard that Quebec is one of the few places where US citizens get treated better than English-speaking Canadians.
So, anyway, Quebec was a French territory before it became part of the Commonwealth, so there's some history of distinction, and there's a long history of it being... less than cooperative as a Canadian province. As I understand it, Quebec currently has a weird status as a non-independent pseudo-nation inside Canada.

 

[Mercutio]

Whoops. Wrong topic. Oh well.