Upgrading to save Energy

D

DougWD

Limp Gawd
Joined
Sep 4, 2005
Messages
502
Hey guys and gals, I have been trying to upgrade my system, not because I want better performance, but to save energy.

After using a Kill O watt meter at the plug and Power Chute APC UPS software, I've decided the two biggest power drains were my Kingwin Mach 1 1000wt Bronze PSU and my GTX 295 video card.

After some quick calculations, I decided to replace the GTX 295 and the PSU with:

Kingwin Stryker 500wt (600wt rating at gold) Platinum PSU:
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=253

And the Power Color AMD 7950 880Mhz 3GB card:
http://www.guru3d.com/articles_pages/powercolor_radeon_hd_7950_pcs_review,1.html

The Power Color card says it needs a 500wt supply. The Stryker is a 500wt supply at Platinum, and actively rated for 600wts, but at Gold. I chose the Stryker because the low consumption efficiency was higher than most al other PSUs, and it's fanless, which means quite too and no fan wattage.

My thinking was that the 500/600 PSU would be a perfect fit for my rig in sig with the new 7950.

Two questions:

(1) The card only uses about 163wts total, so how come recommended minimum 500wts PSU?

(2) Will this PSU be ok?*

*Power draw under load (Prime 95 and OCCt) was around 400wts with my old system.

Addendum:
Yes I understand that the Bloomfield 920 and the X58 are power hogs. But they were the least in the chain, as the PSU and the card were the largest factors in power consumption--especially at idle. The 295 card was consuming more than twice or three times the idle power of the 7950, depending on what you read, especial when driving two monitors (power went up 1200wts when I enabled my second monitor, not to mention running all three!).

Let me say that I also set the clock and voltages to stock on the x58 and 920 and that saved me exactly 3 wts at idle according to Kill O watt and Powerchute. So really not worth it.
 
No, the PSU isn't the biggest factor, it's the CPU and GPUs. You'll find your energy savings to be much greater if you upgrade to a 3770k than replacing your PSU. At low (100w) loads, your current PSU is 77% efficient, which means it will draw 130 watts from the wall. The Kingwin is ~90% efficient at 100w, so it will draw 111 watts. At the theoretical full load of your proposed system (920 @ 4 ghz, 7950), which is ~460 watts, the Mach 1 is ~85% efficient, vs ~91% efficient for the Stryker. This puts load values at ~540 watts vs 505 watts, at 35 watt difference. So effectively, you're saving at most 20 watts while idling, and 35 watts while under load. Not a big difference, something easily saved by replacing an incandescent lightbulb with a fluorescent one, at much lower cost.

Minimum recommended is to account for total system power consumption, plus the fact that people will buy crap power supplies that cannot output their full rated wattage, and old power supplies that do not put out the full rated wattage on the 12v rail.

Now, let's look at what you could save with the 3770k. The motherboard right off the bat will use ~20 watts less, and the CPU itself will idle at 20-40 or more watts less, and at load be up to 100 watts less. The power savings will be much more significant if you switch out the CPU, motherboard, and GPU than if you replace the PSU and GPU.
 
Hey T thanks for being so thorough in your response.

My system is not 4Ghz. It's 3.8Ghz. Of course the power savings will be more significant if I changed the MB and CPU--I already stated that. What I should have said is that the PSU/GPU combo is gig to save more power per my dollar--lol. The PSU is only 114 bucks.

But lets get some real numbers:

My idle right now according to Power Chute is 230wts, driving one monitor. Driving two monitors it goes up to 320 wats. That's the downside of the dual GPs. I checked Power Chute by subtracting the PSU inefficiency coefficient from the Kill O Watt meter, which of course is going to say I'm using more power at the wall, which is correct, do to PSU efficiency. After the deduction, both Power Chute and Kill O Watt came under complete correlation.

Next I loaded the CPU using Prime 95 in Low priority mode and ran OCCt GPU at the same time, which maxed both the Dual GPUs and the CPU at the same time.
TDP = 530wts. (The monitor was not plugged into the UPS and thus did not count for any power draw.

Let's do the math now changing only the PSU:

*230wts idle:
Stryker efficiency at 230wts is 91.2%
Mach 1 efficiency at 230wts is 83.6%
Difference: 7.6%
Idle power savings: 18wts idle. (pretty good)

*This would more using two monitors and more than the single GPU 7950 driving two monitors, but we'll have to wait to see what it draws driving two monitors at idle.


530wts Full Load:
Stryker: 90.4% (but I would never run the Stryker with my current system. And, for practical purposes, I would never be drawing a full 530 watts playing even the hardest games. At 411wts the Stryker does 91.1%. (You can see my problem here when doing calculations).
Mach 1 at 530wts: approx 85%
Difference: 5.4 to approx: 6.0%
Load power savings at 5.8% better eff.: approximately 30 wts.

This is pretty much exactly what you got! :)

So the PSU alone is going to save just about as much as changing the CPU and MB alone--for 114.00USD.

However, this power savings number will be even less with the new video card.

Changing out the entire system, again, you are correct. Although there will be a bit more savings since the new PSU has no fan spinning. 2-3 more watts or a little more.

But changing the MB and the CPU is going to cost me around 450.00/550.00USD+ for a MB level equal to my x58 UD5.

The biggest change would have been to just simply replace the video card.

Dollar to watts the savings for the PSU vs CPU and MB is better deal from an idle point of view (although it will not save more power, sadly). Total spent: 450.00. But the GPU is the single biggest factor, which cost me 330.00 USD. I could only do one or the other.

As I was expecting, the Stryker 500/600wt PSU is going to be more than enough, right?



Tsumi said:
No, the PSU isn't the biggest factor, it's the CPU and GPUs. You'll find your energy savings to be much greater if you upgrade to a 3770k than replacing your PSU. At low (100w) loads, your current PSU is 77% efficient, which means it will draw 130 watts from the wall. The Kingwin is ~90% efficient at 100w, so it will draw 111 watts. At the theoretical full load of your proposed system (920 @ 4 ghz, 7950), which is ~460 watts, the Mach 1 is ~85% efficient, vs ~91% efficient for the Stryker. This puts load values at ~540 watts vs 505 watts, at 35 watt difference. So effectively, you're saving at most 20 watts while idling, and 35 watts while under load. Not a big difference, something easily saved by replacing an incandescent lightbulb with a fluorescent one, at much lower cost.

Minimum recommended is to account for total system power consumption, plus the fact that people will buy crap power supplies that cannot output their full rated wattage, and old power supplies that do not put out the full rated wattage on the 12v rail.

Now, let's look at what you could save with the 3770k. The motherboard right off the bat will use ~20 watts less, and the CPU itself will idle at 20-40 or more watts less, and at load be up to 100 watts less. The power savings will be much more significant if you switch out the CPU, motherboard, and GPU than if you replace the PSU and GPU.
Click to expand...
 
Okay, fair enough. Let's see how long it would take to recuperate energy costs.

Say you game for 2 hours and idle the rest of the time, your computer being on 24/7. We'll compare the Stryker with the 920 system vs the Mach 1 with the Z77 system, both using the 7950. Let's make electric costs 10 cents per kwh, which is pretty high. Comparison is with the 920, Mach 1, and 7950.

3770k idle uses ~50 watts less, and gaming load 75-100 watts.
Stryker will use 20 watts less idle, 30 watts load.

50*22 + 75*2 = 1250 wh, or 1.25 kwh saved per day. That's 456.25 kwh per year, or $45.625 per year.
20*22 + 30*2 = 500 wh, or 0.5 kwh saved per day. That's 182.5 kwh per year, or $18.25 per year.

It would take 10-11 years to recuperate costs on the CPU/MB.
It would take ~6 years to recuperate costs on the PSU.

Now, if you idled ~8 hours a day with 2 hours gaming, with your computer shut off the rest of the time:

50*8 + 75*2 = 550 wh, or 0.55 kwh per day. That's $20.07 a year.
20*8 + 30*2 = 220 wh, or 0.22 kwh per day. That's $8.03 a year.

22-24 years to recuperate costs with the CPU/MB.
14 years to recuperate costs with the PSU.

Basically, the PSU will net you savings quicker, but it still will take a very long time. I do not see a point in upgrading the PSU solely for the purpose of saving electric costs.
 
One reason is because where I live, we get a total of 12Kwh per day, and then we go to a higher level. My power starts at .12 and after 24Kwh it goes to .50 a Kwh!!!

I saved 1Kwh a day simply by taking a Kill O Watt Meter to all of my devices and adding up what it was, then making sure I shut them off after using them, and not letting them go to standby 24-7. Good example is my TV and sound system/DV. Plugged in it was using a whopping 60wts 24-7! I mean some of these devices only consume 1wt, but it all adds up really fast. I save 60 wts by simply turning my APC UPS off after shutting my computer down. Sleeping the UPC was consuming about 65wts. That was totally unexpected.

Right now I'm drawing 375 wts idling from the wall. It doesn't take too long to reach 12Kwh doing that. And that's just my computer. If I paid a flat rate of .12 I might not worry too much. But that isn't the case. In a few months, I will, indeed, replace the MB and CPU too. This is all I could afford right now and it was the biggest bang for the buck--plus giving me much better video performance. I doubt I'll see any performance increases going from my current CPU to the new one gaming and dong everyday tasks. I mean my current system has plenty of headroom to run the 7950.

I'm hoping to cut my idle consumption in half with the PSU and Card update. That would be around 180wts savings. My computer is on working and idling around 5-8 hours a day.
 
Last edited:
Holy crap that's expensive.

However, provided that you go completely into the tier 2 range with your computer's power consumption, it'll take you ~3 years to recuperate costs. At 0.12 per kwh, that's 11 years to recuperate costs. If your situation is mixed, it'll be between 3 and 11 years.

If I were you, I would wait a bit and see if I can get a good deal on a 500w gold power supply, which are significantly cheaper, and the 2-3 percent efficiency loss isn't going to matter much.
 
It gets even better if the PSU and card can actually keep me out of the tier 2 level. Then it's even more economical. Even though, if I'm in the teir 2 or even 3, I'm using less power like you state. My main plan is to try and stay out the upper tiers altogether for a .38 cents less bill per Kwh. the platinum was only 114 bucks. In the long run, it will be well worth the extra cash. My rig now is 5.5 years old. My next rig will use the new PSU and card, plus the new CPU and MB, and I expect to have those for at least half a decade, and the PSU a lot longer--maybe forever--lol.

Tsumi said:
Holy crap that's expensive.

However, provided that you go completely into the tier 2 range with your computer's power consumption, it'll take you ~3 years to recuperate costs. At 0.12 per kwh, that's 11 years to recuperate costs. If your situation is mixed, it'll be between 3 and 11 years.

If I were you, I would wait a bit and see if I can get a good deal on a 500w gold power supply, which are significantly cheaper, and the 2-3 percent efficiency loss isn't going to matter much.
Click to expand...
 
The Gold rated Rosewill Capstone 750 is $100, the Gold rated Seasonic X-650 sometimes go on sale for $90-100, the Platinum rated Rosewill Fortress 750 is $120, the Gold rated Seasonic G550 is $90, Platinum rated Kingwin Absolute Platinum 550 is $90, Platinum rated Kingwin LZP550 is $112.50, and there are many more choices out there.

Really all I'm trying to say at this point is that that Stryker isn't a particularly good value, there are better choices out there.

Edit: Another good one is the FSP Group Aurum 92+ for $105.
 
good thread op :)

I did the same when I bought my kill-a-watt. You can chop a significant amount off your leccy bills :D

I've tweaked all the tvs/monitors in the house to use roughly half the power they used to (64w down from 109w) aswell as most other devices. LED bulbs make a big difference too if you need extra savings :).
 
And you also know it isn't that easy. Did you read the efficiency numbers on all of those models? I also wanted a "fanless" model, which I don't think those models are. And, I wanted the BEST efficiency I could get, within reason. Typically higher wattage units are less efficient at lower wattages. Also, that Stryker has pretty much the best caps and internals money can buy, and all of the components are top notch. I know that 1wt here and .3% efficiency there doesn't seem like much, but when you add it all up, it does matter. Also, I wanted a little more headroom than 500 wts, and this unit is actually rated at 600 at gold, which was perfect. If you drive a Gold the same way, it will most likely drop to silver or even bronze. The Stryker may not be the best bargain, but it is one of the very, very best units made.

As far as getting a 720wt for only 6 dollars more, that is wattage that is wasted, since I'll never, never use it, even if it is only 6 dollars more. Also, again, the higher the wattage, generally speaking the less efficient at where I will be idling 99% of the time, which is I'm hoping around 180 or less wts.

But all of your points are valid.

Tsumi said:
The Gold rated Rosewill Capstone 750 is $100, the Gold rated Seasonic X-650 sometimes go on sale for $90-100, the Platinum rated Rosewill Fortress 750 is $120, the Gold rated Seasonic G550 is $90, Platinum rated Kingwin Absolute Platinum 550 is $90, Platinum rated Kingwin LZP550 is $112.50, and there are many more choices out there.

Really all I'm trying to say at this point is that that Stryker isn't a particularly good value, there are better choices out there.

Edit: Another good one is the FSP Group Aurum 92+ for $105.
Click to expand...
 
THOMO said:
good thread op :)

I did the same when I bought my kill-a-watt. You can chop a significant amount off your leccy bills :D

I've tweaked all the tvs/monitors in the house to use roughly half the power they used to (64w down from 109w) aswell as most other devices. LED bulbs make a big difference too if you need extra savings :).
Click to expand...

True that. Use a power strip and actually shut the power switch off instead of just turning the unit off. Usually you can double power savings. Some power strips use 1-6 watts when plugged in also. Some actually cut the power absolutely.

If you ahve a UPS take teh reading with it plugged in but on, and then plugged in and actually off--where you turn it off manually using the buttons. I saw a 50+ watt drop doing that. Man those things are power hogs on standby. It's ridiculous.

People don't understand that even if it's just "100wats" that alone running 24 hours a day is 2Kwhs!! I only get 12 of those everyday and my energy bill doubles when I go over. What is ironic is that if they unplugged everything they are not using in their house, they may be able to save 1Kwh or more per day.

I'm also looking into solar, although it takes a long time to pay off. I don't care. I hate utility companies being up my ass. I hate it. I think a 6Kwh solar unit in my location--lots of overcast--is 13, 000 USD, which includes hookup to the utility pole and installation. If I'm not home all day, all of that power goes right back to the system on a 1 to 1 ratio. In other words, if I use 6Kwh a day and give back 6, my bill is effectively 0.
 
The LZP-550 has a nearly identical efficiency curve, is rated at 650 watts Gold, and [H]OCP's testing actually showed the LZP-550 to be slightly more efficient (well within margin of error though). [H]OCP's breakdown of the Stryker shows that it is identical on the interior to the LZP-550. The Absolute Platinum 550 is also internally identical, just loses the modularity aspect to cut costs. The fanless power supplies carry a premium that I simply don't think is worth the cost.

Most of these also have a hybrid fan mode, where the fan does not turn on until internal temps get hot enough.

[H]OCP Stryker 500
[H]OCP LZP-550
 
Oh that's another thing. I wanted a modular design, and like I said, I wanted it to be fanless.
 
If that's your preference, then go ahead and get it. I'm just stating that I don't think it's worth it.
 
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