Analyzing Power Use: 80 Plus Bronze vs. Platinumby Jarred Walton on October 30, 2013 8:40 PM EST
I’ve been toying around with updating my computer lately, and one of the topics I wanted to look at was the choice of power supply. For the most part, we’ve long since moved beyond the days where power supplies that cost under $60 are garbage. There are plenty of decent power supplies available, particularly if you don’t mind taking a step down from the latest and greatest in terms of efficiency. Anyway, I was helping a friend put together a new PC the other day and it got me curious.
First, let’s start with the system build he put together, with some input from me. Note that many of the parts were selected based on price and availability on Amazon.com, as that’s where he wanted to purchase the parts (with his Amazon Prime account). In some cases, prices have changed since the purchase a week ago, so shop around as needed. Also note that he used a GTX 780, but I’ve also run some power use tests with just the iGPU as well as with a low-end Radeon HD 7750.
|Custom-Built Intel Haswell PC|
Intel Core i5-4670K
(Quad-core 3.4-3.8GHz, 6MB L3, 22nm, 84W)
|Motherboard||ASRock Z87M PRO4 (mATX)||$135|
Corsair Vengeance 2x8GB DDR3-1866
EVGA GeForce GTX 780 3GB
(2304 CUDA Cores at 967-1020MHz, 6GHz GDDR5)
Sapphire Radeon HD 7750 1GB (Alternative GPU)
(512 Cores at 800MHz, 4.5GHz GDDR5)
Intel HD Graphics 4600
(20 EUs at 350-1200MHz)
|SSD||Corsair Neutron 256GB||$187|
|HDD||Western Digital 2TB Mainstream (WDBH2D0020HNC)||$80|
|Optical Drive||ASUS 24X DVDRW SATA (DRW-24B1ST)||$22|
|Case||Silverstone PS07B (mATX)||$79|
|Power Supply||Antec EA-450 Platinum (450W)||$70|
|Power Supply||Cooler Master GX-450 (450W Bronze) (Alternative)||$49|
|Operating System||Windows 7 Home Premium 64-bit (OEM)||$89|
|Total Price (not including tax or shipping, with GTX 780 and Platinum PSU)||$1592|
Now I’m not equipped to tell you about the quality of voltage regulation, ripple, or anything like that, but I happened to have a 450W 80 Plus Bronze PSU that I could use as a comparison point, so I asked if I could take some quick measurements once the system was put together. He agreed, and I ran through a few typical scenarios, summarized in the table below. (Note that I had to use a Molex to 8-pin PEG power adapter in order to run the GTX 780 on the old Thermaltake PSU; everything worked, but that wouldn’t be a solution I’d be comfortable with long-term.)
|Bronze vs. Platinum System Power Draw (Kill-A-Watt)|
|24/7 Yearly Savings|
|iGPU – Idle||34||27||61.4 kWh (~$7.68)|
|iGPU – Cinebench Single-Core||63||55||70.1 kWh (~$8.76)|
|iGPU – Cinebench Multi-Core||96||86||87.7 kWh (~$10.96)|
|iGPU – Cinebench OpenGL||103||92||96.4 kWh (~$12.05)|
|AMD 7750 – Idle||45||38||61.4 kWh (~$7.68)|
|AMD 7750 – 3DMark||131||121||87.7 kWh (~$10.96)|
|NVIDIA 780 – Idle||48||41||61.4 kWh (~$7.68)|
|NVIDIA 780 – 3DMark||348||325||201.6 kWh (~$25.20)|
For power costs, we’re looking at the worst-case scenario of leaving a system on 24/7, which really isn’t realistic unless you’re talking about a server. For a typical PC that’s on eight hours a day, using the US national average price for electricity ($0.125 per kWh), we’re looking at electrical savings of anywhere from $2.56 to $8.40 per year. That may not seem like much, but considering any decent power supply should last five years and you’re looking at $12.80 to $42 in savings. That’s for a $21 difference in upfront costs, which is much smaller than what we’ve seen in the past for the most efficient power supplies – and note that the price difference tends to grow substantially when you’re shopping for 800-1200W PSUs, though that’s perhaps a topic for another day.
For a system that mostly sits idle, you won’t quite break even by going with an 80 Plus Platinum power supply. However, if there’s a graphics card installed and you do a moderate amount of gaming you should eventually come out ahead. More extreme use cases (e.g. 24/7 Folding@Home) start to rapidly recover the initial investment in a quality power supply, and when you consider the reduced heat and noise that comes with having a more efficient PSU, it’s definitely a worthwhile upgrade. Not all 80 Plus Platinum power supplies are created equal, of course, but generally speaking the electronics and engineering required to get that certification also come with a higher level of quality than what you’ll find in lower efficiency PSUs.
As far as the above system build is concerned, I like most of the component selections, but I’m not totally sold on the case. The Silverstone PS07B looks nice enough, but getting all of the wires connected can be a bit difficult at times. The SSD location on the bottom in particular is a bit of a pain, and the power supply location at the top has some silliness to go with it. The PSU location appears designed to work with the PSU upside down (i.e. fan facing upwards and drawing in fresh air), but the manual for the case notes that if you have a PSU with a 120mm or larger fan, they recommend installing it with the fan facing down. I'm not sure that I've ever seen a PSU with a fan smaller than 120mm where you have ventilation through the bottom, but whatever. If you follow the manual’s instructions, that means the ventilation holes in the top of the case along with the magnetic dust filter are completely pointless. I ignored the instructions and installed the power supply in the most sensible manner for the case, but my advice is to look at some of the other good mATX cases.
The Silverstone PS07B isn’t a bad case, but it’s not perfect either, and for the price I think you can do better. (Apologies to my friend for his taste in cases….) For mATX, I’d at least give the BitFenix Prodigy M or Corsair’s Obsidian 350D a look. If you want a larger case, there are tons of options to sort through, depending on what you're after. Other changes you might consider include sticking with 8GB RAM (2x4GB) initially, going with a midrange GPU like a GeForce GTX 770 or Radeon R9 280X, and there are quite a few motherboard options to consider as well. The i5-4670K still strikes a nice balance between price and performance, and with a bit of overclocking you can stretch its legs a bit further.
Anyway, that’s my little two-for-one special for the day: a quick look at the difference in power use you can expect from 80 Plus Bronze vs. Platinum (obviously 80 Plus Silver and Gold will be closer in power use, but they’re also closer in price), along with a list of parts that I’ve recently used in a friend’s PC. If you have any recommendations or complaints with the build, sound off in the comments.
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Sancus - Thursday, October 31, 2013 - linkA radeon 7950 is nowhere near a gtx 780, these systems aren't comparable.
eek2121 - Thursday, October 31, 2013 - linkOf course it isn't, but my point still stands, he overspent. He went gpu heavy and CPU light. Even if he had purchased a gtx 780, the price would have been comparable with my config vs his config and he would have gotten helluva more bang for his buck.
bznotins - Thursday, October 31, 2013 - linkTotally disagree. If he has settled on the 4670K and has extra $ to spend, better to plough that into the video card. His performance in gaming will be much better with the 4670K & 780 than an 4770K and a 7950. While he might have been able to find some cheaper prices in general, I don't question his CPU/GPU mix one bit.
1Angelreloaded - Thursday, October 31, 2013 - linkWell atleast until we see more than 4 cores making crater holes in the FPS numbers, less than 5 fps isn't really a big deal as the 4670k has no hyperthreading, which in turn may or may not lead to a 4770k upgrade down the line if gaming is the intent.
JarredWalton - Thursday, October 31, 2013 - linkI seriously doubt Hyper-Threading will ever dramatically improve gaming performance before the 4670K and 4770K are both ready for updating. Most games are struggling to use more than two cores properly, so four real cores is plenty, and having four additional logical cores only really helps in a few specific use cases (like video editing/encoding, 3D rendering, and other computationally intensive workloads).
ShieTar - Thursday, October 31, 2013 - linkSo you spent 292$ less for a system with a GPU which is 240$ cheaper, and no 80$ HDD? Does not sound like overspending to me.
On the other hand you seem to have overspent a bit, if you combine 300W worth of electronics with a 600W PSU. What exactly is the chance that any of those work computers will be changed to a CrossFire or SLI system later on? A 400W or 450W PSU could have saved you a few $ and probably keep saving because your systems are probably often working in the 100W to 150W range, where a 600W PSU is unlikeyl to meet its peak performance.
DanNeely - Thursday, October 31, 2013 - linkDepends on your load levels. If your system is mostly at idle a 600W PSU is overkill. If it's mostly at high loads 600W is around the sweet spot. Efficiency is relatively flat from 20-80% although you might get 1 or 2% more from being at 50% under load; but lose out at idle since you're in the sub 20% load zone. However by overspecing the PSU by 250-300W you get enough thermal headroom in the PSU that it's fan never spins up beyond minimum speed giving a slightly quieter box.
SunLord - Thursday, October 31, 2013 - linkShould add some cheap unrated and old psu to better show the impact
JarredWalton - Thursday, October 31, 2013 - linkDidn't have one handy. I stopped trusting lousy PSUs years ago.
1Angelreloaded - Thursday, October 31, 2013 - linkSame, PC power and cooling, Corsair and seasonic, were pretty much always at some point my go to companies.