Will a new psu save much money over and old one.

[CU]

I have two systems that idle most of the day running 6+ yr old psu's. They are a P4 and an Athlon. I see the Corsair CX430 which is 80+ bronze go on sale alot for <$20. Would it be worth it to replace the old power supplies with one of these? How much power / money would it save?

 

[dma0991]

If you could get them for <$20, it won't save you much in terms of cost but it is far more efficient than your current PSU that has degraded over the years. You might not even break even with the $20 spent on the PSU with the savings from the newer and more efficient PSU unless you are using it for another PC in the future.

 

[Ketchup]

I disagree. You didn't say what PSUs the old systems run, but if they are 'generic' units that came with an OEM system or case, they are probably putting out a lot of heat. The bronze unit will not only save on the amount of electricity it consumes, but will save on cooling whichever room they are in. Since we are headed into the summer months, that savings could very well be noticeable.

 

[CU]

They are probably generic. Not Corsair or Antec that is for sure.

 

[Charles Kozierok]

How much power / money would it save?

Potentially quite a bit more than $20.

But the better question to ask yourself is if you really need a pair of systems idling all day.

 

[CU]

The P4 runs mythtv and records cartoons for my kids, so it is easier just to leave it running. The Athlon is really asleep most of the day. It doesn't like hibernate that much due to not always wanting to start back up.

 

[GoStumpy]

Small correction, CX430v2 is 80+, not 80+ Bronze 🙂

 

[mindless1]

If you'd have these two generic PSU powered systems running like this for a while now, odds are fair you're going to have to replace the PSUs before long anyway. I'd get the CX430 next time you see a good sale w/rebate price.

However, P4 wasn't exactly a power efficient CPU architecture and many of the Athlon era motherboards had HALT idling crippled so they wasted power even idling. I'd be thinking about whether it's time to consolidate both of these systems into one newer build. Given the US avg. electrical cost of $.12/KWH, your yearly savings running 24/7 would be about $1 per watt reduction.

Since no system lasts forever, if you factor for the parts cost as a sum divided by the # of years you use a system, your savings on the power bill might exceed the yearly system parts cost.

 

[Ketchup]

Yeah, get a VM or two running on a newer build to handle all your needs.

 

[Zap]

The P4 runs mythtv and records cartoons for my kids, so it is easier just to leave it running. The Athlon is really asleep most of the day. It doesn't like hibernate that much due to not always wanting to start back up.

How about a single new power efficient system that can run all that? What does MythTV need? Would it run on a Brazos?

 

[BrightCandle]

Lets say you save 20% just in the PSU change alone, that is your old one is only 60% efficient and the new one is 80% efficient. It is more than likely less than that. Because the machines are mostly idle lets also guess that they probably only pull 150W from the wall constantly. These aren't modern chips and they are quite hungry but its also probably a high as an estimate. You can get more accurate details by reading the label on the PSU and measuring using a watt meter.

Given those two guesses you are looking at saving (150/0.6 - 150/0.8) 63W with a new PSU. Which when running 24/7 means daily you are consuming an extra 1.5 Kwh than had you bought the new PSU. Around these parts we get charged about 12 pence per kwh and my guess is in the US its about 15c? Again feel free to put in your own figures

Total per day extra is = $0.15 * 1.5 = $0.225
Time until break even on new PSU ~= 89 days

More accurate numbers will give you a better estimate. You can do the same thing with replacements for the machines, work out the power savings based on benchmarks done by reviewer and compare the cost and work out how long you'd have to keep it before it saves you money in power. More often than not it pays off in under 6 months.

 

[LurchFrinky]

I haven't checked his numbers, but BrightCandle has the right idea. It's not whether you will save money by switching to the more efficient PSU, it's how long it will take to get a return on your investment. If electricity is overly expensive where you are, or if you think you can keep these systems running for several years, then the decision is easy - upgrade the PSU.

However, since you are considering long-term cost savings, you might think about upgrading your systems to low-cost, modern, energy-efficient systems. There have been several threads in General Hardware discussing low power HTPC setups. The general consensus is to build around a G530 for a little more than $200. With an idle power draw around 30W from the wall, you will be saving money faster, even though you paid more up front. You will still break even at about the same time as the PSU alone, but you will have a more responsive system that will definitely last several years.