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PSU do i need -5v rail ?

Last response: in Components
November 23, 2011 9:47:37 AM

Hi guys
For what is the -5V rail in psu used ? do i need it ?

More about : psu rail

November 23, 2011 12:45:16 PM

I just watched on my motherboard
In my ATX 20+4 pin connection to her is writen on one of 20 points -5v rail. Soo i need -5v right?
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a b ) Power supply
November 23, 2011 12:57:52 PM

Not unless your motherboard is very old and you still have ISA cards.
November 23, 2011 2:28:38 PM

My motherboard is GA-H55M-S2 from Gigabyte
a b ) Power supply
November 23, 2011 3:05:59 PM

That motherboard is too new to have ISA slots. In addition, it uses a 24-pin PSU connector; newer PSUs normally don't have a wire on the -5v pin. Did you ask the question because you're getting a new PSU that doesn't have a -5v rail?
November 23, 2011 3:34:35 PM

yes and in user's manual of my motherboard in section (1/2 ATX_12V/ATX (2x2 12V power connector and 2x12 main power connector) is information about the 24 pin psu connector from 1 to 24 pin
1- 3.3v
2- 3.3v
3- GND
4- +5v
5- GND
6- +5V
7- GND
8- Power Good
9- 5VSB ( stand by +5v)
10- +12v
11- +12v ( only for 2x12-pin ATX)
12- 3.3v (only for 2x12-pin ATX)
13- 3.3v
14- -12v
15- GND
16- PS_ON ( soft on/off)
17- GND
18- GND
19- GND
20- -5V
21- +5V
22- +5V
23- +5V (only for 2x12-pin ATX)
24- GND (only for 2x12-pin ATX)

In 20 there is -5V

soo ?
a b ) Power supply
November 23, 2011 7:32:17 PM

So it isn't used because you can't install ISA cards. Do you know what ISA cards are? They are the type of cards that were used before PCI 1.0. Does your PC work properly?
November 23, 2011 7:48:29 PM

I have currently i3-540 + 4gb ram and i am buying a new video card GTS 450
And to all that i need a new psu
soo the main question is... what will be if my psu... ups no -5v rail =)
and 1 question about psu. Thay have filters like PFC / OVP /OCP /UVP /OLP /SCP etc

If my psu will have only this OLP /OVP / SCP... will it be enough?

And what about Tracer HIghlander brand with 500W with all this filters PFC / OVP /OCP /UVP /OLP /SCP should i buy it ?
November 23, 2011 7:57:34 PM

Do not worry about the -5Volt thing, it does not matter at all.

Do not buy a Tracer Highlander brand PSU. You should never buy an off brand PSU, they commonly fail, taking the rest of your system to the grave with them.

Buy an Antec, Cooler Master, Corsair, or at the cheapest (marginal) OCZ, do not go any cheaper than those brands.
a b ) Power supply
November 23, 2011 8:04:59 PM

You don't need -5v; you would only if you had a PC older than year 2000 (and even those rarely had ISA cards).

You definitely want a PSU with Active PFC, i.e., no 115/230v switch as found in cheap PSUs. Any quality ATX 2.01 or newer PSU will work just fine as long as it is powerful enough.

Who manufactures the Tracer Highlander 500w and what are the specs? 500w means nothing; cheap PSUs rarely achieve their rated output while quality PSUs usually exceed it. A quality 450w PSU meets your requirements.

Don't you have access to PSUs manufactured by Antec, Corsair, PC Power and Cooling, etc.?
November 23, 2011 8:49:24 PM

my budget is allmost over cause i buyed new video card and 2 gb ram
what do you think guys about
TAKE ME 500 SILENT 12cm [TAKZAS30889] ? cause this my budget will allow to buy
PFC avaible and 27.5a on +12v Rail

November 23, 2011 8:56:34 PM

Do not buy an off-brand PSU.

Acceptable companies include Antec, Corsair, PC Power And Cooling, XFX, OCZ, and Seasonic. A cheap, generic brand power supply will almost always burn out in a short period of time, often taking the rest of the system out with it.

If you don't have any money left, then wait until you do.
November 24, 2011 5:51:51 PM

hmm i decided not to buy... YET!
but guys
i got few questions
Cause... I think my PSU will be enough for my configuration. Dunno if its true
I have i3-540 and intel says it needs 73W
The new Gts 450 that i buyed - needs 106W
Motherboard GA-H55M-S2 Gigabyte
2 sticks ddr3 ram
and thats all
My psu has on +12v rail 20A and that gives 240W

106+73=179+(HDD+DW-RW+ddr3x2) 40W ?? = gives around 219W right?

Soo here are my questions

1. How often will the CPU and GPU be at max load ? meaning that i intend to play new games on max? ( i have 1240x1024 i can do this )

2. Are my calculations about 219W right ?

3. Will be there a problem if my +12v rail on PSU will be used allmost at maximum? My PSU has 500W and only 240W on +12V rail
November 24, 2011 7:18:18 PM

no one knows ? cause i dunno should i launch this configuration or not
a b ) Power supply
November 24, 2011 8:14:18 PM

A PSU with a single 20A on the +12V rail is not a 500W PSU. Are you sure that it doesn't have another +12V rail? If not, then it's not good enough.