Is 125W Combined Power on the +3.3V and +5V Rails Enough?

O

Outbreaker

Limp Gawd
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Mar 22, 2012
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472
HI, :)

After shearing around i thought i found a good power supply but now i'm not so sure anymore if 125W combined power on the +3.3V and +5V rails is enough if i have this components connected to the motherboard:
1 USB 2.0 - Keyboard
1 USB 2.0 - Mause
1 USB 2.0 - TV SmartCard
1 USB 3.0 - Smartphone (Charger)
6 SATA 3.0 - Hard Disk Drives
1 PCIe x16 - Graphics Card
1 PCIe x1 - Sound Card
1 PCIe x1 - WLAN Crad
1 PCIe x1 - Bluetooth
1 PCIe x1 - Hybrid TV Card
 
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A modern computer primarily runs off of the 12v rail. No one cares about the 3.3v or 5v rail unless you're trying to run an old high-end P3 system.
 
Note how I said primarily. All the large power components draw their power from the 12v rail. If a motherboard includes a 25w capable USB port, it's usually limited to two or three. Besides, how many ipads are you going to be charging off of one computer?
 
It's not about the USB only like i said Hard Disk Drives are also using the +5V rail but i don't know how much Watt they use and i'm also sure there are other computer components using 5V and 3.3V rail. 40W are already gone from the 125W´only for the USB devices.
 
Not much. All of your PCI-E devices run off of the 12v rail. CPU and motherboard chipset run off of the 12v, and RAM probably does as well.

Therefore, you should focus on your 12v rail, unless you have an abnormally large amount of hard drives (20+).

BTW, smartphones max out at 1 A. It's the ipad and other tablets that use the USB port to charge that draw up to 25w. That means your smartphone is 12 watts, keyboard and mouse are much less, your smartcard might use up to 12 watts (if it works on any USB 2.0 port, it will max out at 500 mA, or 6 watts).
 
PCIe 2.0 x1 can also deliver 5V and 3.3V if needed. The power supply i plan to buy has 63A on the 12V rail so that should not be an issue. It's really hard to find a statistic on how much a PC is using on the 3.3V and 5.5V rail.
 
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Because, as I said, it's hardly relevant, and you're seriously thinking way too hard about this.

For that matter, what power supply are you planning on getting? Rather than worrying about how much wattage it has on the 3.3v and 5v rails, you should be worrying about whether or not it's a good quality power supply.

Good quality power supplies are built to be able to handle 99% of desktop 3.3v and 5v rail needs. Only servers require more wattage on the minor rails, and they're dedicated to powering something like 20 or more hard drives. You do not need to worry about having enough power on the minor rails.
 
I'm looking to buy the "Seasonic X-760" but i'm worried because most power supplies have 150W and a few even 180W combined power on the +3.3V and +5V rails.
 
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Have you added up all of your component wattages to see if you'll be anywhere even near 125w?
 
Tsumi said:
Not much. All of your PCI-E devices run off of the 12v rail. CPU and motherboard chipset run off of the 12v, and RAM probably does as well.

Therefore, you should focus on your 12v rail, unless you have an abnormally large amount of hard drives (20+).

BTW, smartphones max out at 1 A. It's the ipad and other tablets that use the USB port to charge that draw up to 25w. That means your smartphone is 12 watts, keyboard and mouse are much less, your smartcard might use up to 12 watts (if it works on any USB 2.0 port, it will max out at 500 mA, or 6 watts).
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USB is 5v so a smartphone @ 1A is 5W, and normal USB @ 500mA is 2.5W.

Outbreaker said:
I'm looking to buy the "Seasonic X-760" but i'm worried because most power supplies have 150W and a few even 180W combined power on the +3.3V and +5V rails.
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125W is actually quite a bit of power. Most HD's pull from 12V and pull max of ~1.1A @ startup and significantly less when running. The seasonic X760 is a great PSU. Although I would maybe suggest looking at one of the newer platinum designs. Here is the Seasonic Platinum 860, http://www.newegg.com/Product/Product.aspx?Item=N82E16817151111 It is $50 more than the X-750 Gold @ http://www.newegg.com/Product/Product.aspx?Item=N82E16817151087 but it would be money well spent IMHO on a high end system. These days I like to go as efficient as possible when building new systems.

EDIT: It looks like there is a Platinum 760 out now @ http://www.newegg.com/Product/Product.aspx?Item=N82E16817151120 I would go with that as it's only $20 more than the gold one.
 
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Lol woops, I was multiplying by 12 instead of 5.

Anyways. 760 watts is way overkill for any single GPU system. What are your exact specifications?

And stop worrying about the minor rails already. While I can see where you're coming from, it's just needless fear.

Seasonics are one of the best, but there are several other really good ones as well. Super Flower has been a major competitor lately, and their units are often cheaper than Seasonic units.
 
760W isn't really an overkill a frende of my has a 2 year old computer (1GPU&1CPU) with less components and he has around 400W on full load. And it's always a good idea to stay under 80% of the PSU load. And the Seasonic 660W is also only 10€ cheaper than the Seasonic 760W.

SuperFlower has no OCP, a MOV and similar protections:
Note that the only direct 80 Plus Platinum alternative comes from SuperFlower/Kingwin. The Kingwin LZP-750 (made by SuperFlower) is just as expensive as the Enermax Platimax 750W (slightly more, actually), and it's missing some features such as OCP, a MOV, and similar protections. Beyond that the LZP-750 (or SuperFlower Golden King Platinum—which is even worse than Platimax as far as names go!) offers fewer connectors. For that reason we would recommend the Platimax 750W, but only for those who demand every ounce of efficiency. If you're more of a mainstream user and can live with 1-2% less efficiency, you can certainly save some money, but it's clear that Enermax is a leading company for high-quality products.
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http://www.anandtech.com/show/5252/enermax-platimax-750w-80-plus-platinum-arrives/6
 
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Again, exactly what components are you powering?

Power draw from the wall =/= power draw of components. If he has an 85% efficient power supply, he's only pulling 340 watts from the power supply.

Also, unless you plan on staying at full load 24/7, it's not a good idea to get a power supply that will never reach 80% load. It's just wasting money.
 
My PC is 24/7 on and the Hard disk drivers take about 25W at startup an because i use a backup program the Hard disk drives startup every 3 hours and with 6 Hard disk drives that's 150W, and i do also have more components in this PC than a normal user.
If i buy a PSU i calculate want everything would use at max and for my PC this would be around 500W and if i want to use a second graphics card in the future then there is no way around a 760W PSU.
 
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Modern 7200 RPM hard drives require at most 10 watts during aggressive usage. 5400 RPM hard drives use less than 8. SSDs use even less.

Also, tell me what your exact components are already. I don't care if you think you need more, without knowing the exact components I can't begin to figure out what you actually need if you don't give me this information.

However, if you're dead set on it, just get it and don't bother posting back here, because you're wasting both our time.
 
Tsumi said:
A modern computer primarily runs off of the 12v rail. No one cares about the 3.3v or 5v rail unless you're trying to run an old high-end P3 system.
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don't some of the AMD 462 hotrods need some juice on those rails as well?
 
Like Tsumi said, 7200rpm HDDs running full blast will at most use 10w, so you're looking at 60w max for your HDDs.
 
jojo69 said:
don't some of the AMD 462 hotrods need some juice on those rails as well?
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Well, P3 era boards. Back then, the CPUs ran off of the 5v rail. It was with P4 that Intel and AMD switched to 12v, that's why you occasionally see the 4-pin CPU connectors labeled as P4.
 
Here is a really good link about the how much Watts a HDD uses:
http://www.xbitlabs.com/articles/storage/display/1tb-2tb-roundup-2_16.html
With all the stuff i have 125W should be no problem on the 5v and 3.3v rail but it would not hurt if they would push the 5v and 3.3v rail to 200W.

Does some one knows a good online shop in europe where i can get the Seasonic X-660 or X-760 or X-860 PLATINUM for a reasonable price? If not then i buy the Seasonic X-760 Gold.
 
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I see only .9 amps max startup usage on the 5v rail for a 7200 rpm drive. The rest is on the 12v, so you don't need to worry about it. So that's 4.5 watts per drive on the 5v rail. Read and writes use less than 3 watts each on the 12v rail.

Again, only a server requires strong minor rails. Your desktop doesn't have enough drives to reach server status. If it did, you should be looking at server power supplies along with a RAID card that supports staggered spinup.
 
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