Since I got this Antec Earthwatts EA-650 (cheaper at the time, mind you), I've been curious what 12V rails are powering what components, and how the two rails add up. You see, each rail should be theoretically capable of providing 456W each (38A * 12V), but the power supply is only rated for 650W, not 912W , so I must be missing something.
I assume that my GPU is being powered by both rails, and the CPU + motherboard are on one of the two, but I'm not too sure.
the Limits are not inclusive... that is, your load can only go past 650 if nothing else is using it. (Actually, sometimes it can go higher, but obviously that is likely to cause problems).
Anyway, for rails, +3.3v is usually used for chipsets, memory, PCI/PCI-E cards, and other chips; +5 is used by Disk drive logic, SIMMs (much older memory) PCI/PCI-E cards, the Southbridge, VRMs, and various chips on the motherboard. +12v is used almost exclusively for drive motors and high output voltage regulators.
the Limits are not inclusive... that is, your load can only go past 650 if nothing else is using it. (Actually, sometimes it can go higher, but obviously that is likely to cause problems).
From what I've read on Tom's Hardware, the rails can't "borrow" from each other.
To my understanding, the 3.3V and 5V rails very little power these days, as the CPU, GPU and peripherals are on the 12V rail, which means it's almost all the power. As far as I know, this is why it's good to have a PSU with most of its power delivered over the 12V rail.
From what I've read on Tom's Hardware, the rails can't "borrow" from each other.
I never said they could.
The maximum rating of all the rails put together will almost always exceed (sometimes by double) the maximum rating of the PSU. For example, if the 5v had a "maximum" that calculated to 300 watts, the 3.3v might have a limit that calculated to 300 watts as well, but if the PSU is 500 watts, it's a bad idea to draw more than a total of 500 watts.
Graphics cards get their 12v supply from the additional connector.
To my understanding, the 3.3V and 5V rails very little power these days
CPU and motherboard run on 3.3v and 5v. Most motherboards have a VRM that draws 12v for use as 3.3v and 5v, so the draw will appear on 12v. Any power supply you can buy today will deliver most of it's power on the 12V rail.
The maximum rating of all the rails put together will almost always exceed (sometimes by double) the maximum rating of the PSU. For example, if the 5v had a "maximum" that calculated to 300 watts, the 3.3v might have a limit that calculated to 300 watts as well, but if the PSU is 500 watts, it's a bad idea to draw more than a total of 500 watts.
Graphics cards get their 12v supply from the additional connector.
CPU and motherboard run on 3.3v and 5v. Most motherboards have a VRM that draws 12v for use as 3.3v and 5v, so the draw will appear on 12v.
I assume that my GPU is being powered by both rails, and the CPU + motherboard are on one of the two, but I'm not too sure.
Anyway, for rails, +3.3v is usually used for chipsets, memory, PCI/PCI-E cards, and other chips; +5 is used by Disk drive logic, SIMMs (much older memory) PCI/PCI-E cards, the Southbridge, VRMs, and various chips on the motherboard. +12v is used almost exclusively for drive motors and high output voltage regulators.
From what I've read on Tom's Hardware, the rails can't "borrow" from each other.
To my understanding, the 3.3V and 5V rails very little power these days, as the CPU, GPU and peripherals are on the 12V rail, which means it's almost all the power. As far as I know, this is why it's good to have a PSU with most of its power delivered over the 12V rail.
I never said they could.
The maximum rating of all the rails put together will almost always exceed (sometimes by double) the maximum rating of the PSU. For example, if the 5v had a "maximum" that calculated to 300 watts, the 3.3v might have a limit that calculated to 300 watts as well, but if the PSU is 500 watts, it's a bad idea to draw more than a total of 500 watts.
Graphics cards get their 12v supply from the additional connector.
CPU and motherboard run on 3.3v and 5v. Most motherboards have a VRM that draws 12v for use as 3.3v and 5v, so the draw will appear on 12v. Any power supply you can buy today will deliver most of it's power on the 12V rail.
I see what you're saying.