Power Supply.

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Power Supply.

Postby Felix Jongleur » Fri Apr 16, 2004 7:40 pm

Hi! I have an underpowered system.

Whenever I plug in 2 of the huge SUNON fans that suck a lot of power, Windows fails to boot or, boots slowly then crashes. So, when I unplug them it works fine! And if I plug in other crappy fans it works fine too!

This sounds like a powersupply problem to me, but the fans are rated at 12V+ and so is the CPU/Mobo, isn't it?

I saw several 550w PSUs from Forton and Antec but they only have 18A on the 12v+ line, and I wonder, will it do worse than my 350w PSU with 26A on the +12v? (It has +3.3V@32A; +5V@32A; -5V@1A; +12V@26A; -12V@1A; +5VSB@2.2A)

Now, which PSU should I get? I'm willing to spend up to $150ish for a very good one that can have good 120mm fans that suck power like crazy.

Thanks in advance!
-Felix
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Postby Mr T » Fri Apr 16, 2004 8:25 pm

The Antec and the Forton ones should work fine, however are you plugging the fans ininto the motherboard? Your 350w should handle those babies no problem, but it could be failing..... :cry:
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Postby profofpcs » Fri Apr 16, 2004 8:28 pm

did you try and plug in only one fan? maybe ones got an internal short? do you have molex plugs on them? if so, plug them into the power supply cable and not on the mobo.
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Postby don'tknowmuch » Fri Apr 16, 2004 8:36 pm

This may help to figure out your configuration on your system to choose the right psu

A 7200rpm HD draws around 20 watts, this 20 watts includes both the 5v & 12V rail.

HD and CD's generally are figured at 2 Amps per device, let’s brake this down some.

Spin-up: 12V x 1.3A + 5V x 650mA = 19W

Read/Write/Idle: 12V x 350mA + 5V x 700mA = 7.75W

Seek: 12V x 675mA + 5V x 725mA = 12W

Those would be typical for a 7200 rpm IDE drive. As you can see a HD requires more power at start-up then during actual operation. This is why sometimes a PC takes a few tries to start up before it will actually make a successful boot and once it boots to windows all seems well or sometimes a occasional lock-up or restart, which would indicate a weak/ bad P/S.

Now to find the power used by the CPU you can check either AMD or Intel for the spec sheets on that CPU or you can follow this link that has tons of CPU ratings, http://users.erols.com/chare/elec.htm

Some more basic mathematics… When a 12-volt circuit is drawing 10 amps, it is consuming 120 WATTS of electrical power. 12 Volts X 10 Amps = 120 WATTS.

This is the formula: P = E x I
P - Watt (power)
E – Voltage (electrical pressure)
I – Amperage (current flow)

Serial/PS-2 ports draw <35mA and if you have USB ports then they have a maximum of 500mA per port, again only if they are used- no use means no draw.
The PCI slots are allowed 5A of the +5V, 0.5A of the +12V and 7.6A of the 3.3V Max per slot, again that is if the slots are used. So if the serial ports, PS-2 and USB ports are being used you are looking at around 5A draw on the MB, which would be around 20 Watts.

So now we can add things up. (This is just an example of a basic system)

MB=20W
CPU= 60W, used as a norm.
HD=20W
CDRW=25W
DVD=20W
Graphic card=15W
RAM 10 Watts per 128 MB
Network Card 5 Watts
Average per PCI Card 8 Watts

Total around 200W for this example.
Now this will fall on different rails and that is were things get tricky, because as you see in my above break down of the HD you see that a HD use's both the 12V & 5V rail. This is why it is important that the 12V rail be at least 18 Amps if you plan on having more then 1 HD and case fans. Then you have the 3.3V & 5V rails that need to be strong too, the 3.3v rail is actually not so important with newer DDR MB and today’s CPU’s as it is mainly supplying the PS-2 ports power as well as some device cards. Most newer MB use the 5v and 12v rails mainly to supply the demands of today’s devices
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Postby Felix Jongleur » Sat Apr 17, 2004 7:36 am

These fans are huge, they move 130ish CFM and they are 1 inch deep/thick. They have 4-pin molex connectors. They also have their own strand of wires.

My PSU comes with 6 strands of wires, of 2 molex each and 2 have floppy.

Now, I have the CD-Rom and floppy on the same, videocard on another, harddrive on another, and finally the fans on each their own. Thats a total of 5, I have one strand left and that's tucked away.

My motherboard uses the regular huge plug, its 24 pin? Plus a smaller 4 pin one that is square.

I tried plugging one fan in, but it was still slow and crashed. Then I take them out and put some Antec weaklings in it and BooHoo they work.

So, I wonder is it the fans that are shorting? Or is it the PSU that's giving up?
Abit AV8 BIOS.26
A64 3000+ Winchester @ 2.2ghz
HyperX 2x512mb Pc-3200 2.5-3-3-8 @ 250mhz
eVGA 6800GT @ 374/1.03ghz
40gb WD400 IDE
80gb WD80 SATA
Audigy 2 OEM
WinXP Pro SP2
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Postby ZieClaw » Sat Apr 17, 2004 7:41 am

About youre PSU whats the brand of it? :wink:
pentium 1 66 mhz uber powerfull -.-

rig specs:
msi kt6 delta-lsr mobo
AMD Athlon xp 2600+ barton
512 mb kingston value ram
120 gb 7200 rmp 8mb sata wd hdd
fic radeon 9600 pro 500/368
philips 4/2/32 cd-rw
msi 16x dvd rom
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Postby profofpcs » Sat Apr 17, 2004 10:32 am

its in his sig, Enermax EG365P-VE, a very stout power supply to say the least. can you get any other 120MM fans to try? ive got 12 fans in my case running in my sig and there's still power left. that or you just need more power.
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Postby ZieClaw » Sat Apr 17, 2004 10:50 am

Hmmmm yeah enermax is good 8) *Hates Q-tec whit there nice peak amps* :lol:
pentium 1 66 mhz uber powerfull -.-

rig specs:
msi kt6 delta-lsr mobo
AMD Athlon xp 2600+ barton
512 mb kingston value ram
120 gb 7200 rmp 8mb sata wd hdd
fic radeon 9600 pro 500/368
philips 4/2/32 cd-rw
msi 16x dvd rom
Sweex Xenon XB
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Postby Felix Jongleur » Sat Apr 17, 2004 5:26 pm

Yes, I have 2 Antec 120mm that came with my case. (Its the grey one with a flimsy/filmsy plastic door and has a 350W PSU. My friend got one of those cases so I "borrowed" his fan. Now I have 2 identical 120mm Antec fans.)

The PC runs as fast with or without them, however the only thing they have printed on them is "1.6" which I think means 1.6A on the 12V line, the sunon have 6.8A on 12V.
Abit AV8 BIOS.26
A64 3000+ Winchester @ 2.2ghz
HyperX 2x512mb Pc-3200 2.5-3-3-8 @ 250mhz
eVGA 6800GT @ 374/1.03ghz
40gb WD400 IDE
80gb WD80 SATA
Audigy 2 OEM
WinXP Pro SP2
Enermax EG465AX-VE 460w
Felix Jongleur
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Location: Washington, U.S.

Postby profofpcs » Sat Apr 17, 2004 5:29 pm

i think those sunons are dragging you down.
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depression is just anger without the enthusiasm
anger is just danger without the "d"
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