Gaming Madness Community Forum

I was looking at some powersupplies today and seen this:

+3.3V@30A, +5V30A, +12V@70A, -12V@0.8A, +5VSB@3A

Supposing I purchased this powerupply, how would you know which one is the 70A one? Or does it not matter and those are only there so you know how much power you can draw?

well as amps are very important. what is the watts on it i am assuming that with a 70 amp 12 volt rail it is like 1000+ and you can tell by the box and that many watts + amps only go into the 12 volt rails for video cards.

as the standards go, the +12v lines will be the yellow wires (red 5v, orange 3.3v)

the +5vsb is used only for the 'always on' logic of the motherboard, such as the parts watching the power switch,
the -12V is also only used for special functions of the board
so you can generally ignore these values when looking to add more hardware.

to get the wattage of each line you can multiply the voltage and wattage (e.g. 12v * 70a = 840w)

the total wattage of the card adds the values for all lines out

Its a regulated psu so you can draw as much power as you below those values for each line. you have to be careful when you approach or exceed the limits because that leads to excess heat in the psu which is hard to monitor, and causes a ripple in the voltage level which can create some instability in your system.

So generally the main things you want to look at 1) the totally wattage, and 2) the wattage of the 12v (since this runs the power hungry things: cpu, gpu, etc)
the 5v is less important unless you are running a monsterload peripherals, like say, 12 hdds in a storage server.


as far as my system goes: I run a core2 duo, 8800gts(the older one), with the hdd's, off of a 350w (hey probably underrated for the job, but it works...for now)
I have a string of led's wired up to the 12v line too for some desk lighting ( about 2-4watts) and I can watch em flicker as my system goes under a tough load(btw: that is NOT a good thing :p ), like loading crysis off(lots of disk reading, memory functions, gpu full out, cpu chuggin' etc)
yeah, left my gaming rig back at home this semester, thought i would get more work done, then I found that win7 can handle the memory managment to make crysis:warhead playable standard specs with only 1GB of ram :p

and for a cheap regulated psu for those who like lab work and are on a budget; you can short the green line and the ground to turn the power supply 'on' when its not connected to a pc. You have all the voltage levels for logic and regulated 12v for any low voltage power projects.

I am wondering all this because I'm trying to get the right PSU for the most recent build I am working on. So far the build contains...

CPU: i7 -920

Ram: 6gb

SSD: 30gb (for OS)

HDD: 1tb (for files)

GPU: GTX 260 (216 shaders, 55nm) in 2 way sli (evga says this card needs 36amps on the 12v rail)

Mobo: 6 ram slots, X58

PSU: Which one do you think will be good for my build?

http://www.newegg.com/Product/Product.a ... 6817139006

http://www.newegg.com/Product/Product.a ... 6817139009

the first one would be adequate and would save you like $30

I am trying to get a PSU that will work with the upcoming video cards when I need to upgrade. So, do you think I should get the 850W?

well full throttle the 280 takes about 20 amps (240watts)
so with 2 way sli you're looking at 40amps for graphics
your 260 takes about 15amps per card (180 watts)
that 36amps min. must be for the entire system (36 -15 leaves 20 for everything else)

both psu's will be plenty right now.
I really like the single rail 12v, that way you aren't micro budgeting the wiring, making it a much easier build.

even with 20amps left for everything else (an upgrade to two 280 and a 60a 12v rail) that should be enough unless you want to add a few more hdd's(and these take less than 2amps each typically) or up the voltage on the i7for over clocking.

I only see you running into trouble if you decide to upgrade to a 3 way sli.

<offtopic> damn the x58's have 6 ddr3 slots! right, 3 mem channels. wow I really need to get a job and upgrade</offtopic>

Go with the higher one.......Especially if you intend on upgrades like max'ing out your ram or upgrading to an even better card (or more cards if you intend on running a larger screen at a higher resolution).

Allright well then its decided, I am going for the higher watt PSU. Thanks for all the help guys

paint i have ordered the first cosair 750 watt ($129)on neweg and am waiting for delivery.
using Asus m4a79 socket am2+ motherboard
4 gb corsair xms ddr2 240 pin 1066 ram
evga 9800gt factory superclocked 1g ddr2 video card
AMD PHenom x4 quad core 2.4G
still wont boot i think it is the psu issue.
will let u know what happens (rock)