20 pin PSU 24 pin Mobo?

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westyUK1
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Joined: Mar 13 2006

Hi
I'm building only my second PC and there are things that have changed since my last system. I bought an ATX case ( Arctic Cooling t2 Silentium Midi Tower with 450W Seasonic Silent PSU ) and a Asus A8N-SLI SE Nforce 4 motherboard. It turns out the Mobo needs a 24 pin connector (ATX 2.0 compliance?) and the PSU is only 20 pin. Question is, is a simple 20 to 24 converter the only change I need to make to get things running. Also the power supply plug is a US 2 prong. Can I use a travel adaptor or is that too risky with the high voltages? Would it be safer to just get a new lead?

I'd appreciate any help.

harlequin
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Joined: Aug 16 2000

1. new lead
2. 99% sure you need a new powersupply

Gary MacKenzie

sepulce@hotmail.com ( an account only used for forum messages )

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Philip Woods
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Joined: Feb 7 2002

I have a Asus A8N-SLI M/board on my latest setup.
The 20 pin plug will fit the 24 pin socket !
With the socket latch ON TOP ! Push the PLUG in the Right side of the Socket !
It will only go in on the correct side as it is polarised.
As Gary states a new lead, they are not expensive.
Regards,
Philip

westyUK1
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Joined: Mar 13 2006

Thanks for the info. My other concern is the PSU power, I'm only using a single card but not sure if it will be enough as I read the converter splits the 12 rail into two. The 12v rail is 17A, plus +3.3V 28A, +5V 30A, -5V 0.5 A, -12V 0.8A, +5V 2A. Can it damage the components if I try it first?

Vimeous
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Joined: Mar 10 2006

I agree with Gary. New lead without question. Also make sure you get a surge protected extension lead. You don't want power spikes killing your nice new toy! :)

Most 24pin capable PSU's have the standard 20pin plug with a clip-on 4-pin extension. This means they'll work in older boards.
Conversely it means new 24pin sockets will accept 20pin plugs BUT you must ask yourself at what cost? Have a good look through the ASUS site and see if you can find advice on what happens if you use a 20pin connector.
Again I agree with Gary, chances are you'll be looking to swap that PSU. If so I suggest Tagan from my own experience despite the cost but there are many decent manufacturers out there to try.

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westyUK1
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Joined: Mar 13 2006

Unfortunately the PSU is hard wired into the case

see here > http://www.scythe-usa.com/product/case/002/acst2.html

meaning modding would be required to fit a new one. I've bitten the bullet and am sending the case back. I've ordered a Seasonic S12 500W Silent ATX2.0 and a CoolerMaster Centurion 532 Aluminum case. The PSU is a bit more than I wanted to spend but I know its one of the best for that range.

Vimeous
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Joined: Mar 10 2006

Sounds like you made the right choice to me. It also means you've more scope for change in the future.

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westyUK1
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Joined: Mar 13 2006

The online manual for the case/PSU (it doesnt come with one... :rolleyes: ) says:

Mainboard, 20 Pin Connector:
Can be used on all main boards with 24 pin connector. Certain mainboard manufacturers require a 4 pole powerplug (HDD1-3 or VGA board plug) to be installed additionally when using a 20 pin connector.

I'm pretty confused by this, does that mean the 20 pin can plug into the mobo leaving the 4 remaining pins completly open?

Vimeous
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Joined: Mar 10 2006

The extra 4-pin sockets began to be added when gfx cards suffered stability problems. This was because with the standard 20-pin the motherboard could not supply enough power to the AGP slot when the cards were pushed hard

I've read through the S12 datasheet () and if you look at the seond page you'll get your answer.
Listed as the all-in-one connector design the S12 offers a bunch of options. The important one for you is the 20P+4P pair of connectors. Check you motherboard to see if there is an additional 4-pin power socket near the backplane sockets. That is what would previously have been used for the additional 4-pin connector.

In the UK ASUS sell an A8N-SLI in standard, deluxe and premium flavours. Having checked their specs they all have a single 24-pin and an additional single 4-pin connector.

ASUS A8N-SLI SE Manual wrote:
• Do not forget to connect the 4-pin ATX +12 V power plug; otherwise, the system will not boot.
• If your power connector is 20-pin when you use two graphics cards, do not forget to connect the 4-pin ATX +12 V power plug to the EZ Plug™; otherwise, the system will be unstable. See page 6-5 for details.
• Use of a Power Supply Unit (PSU) with a higher power output is recommended when configuring a system with more power-consuming devices. The system may become unstable or may not boot up if the power is inadequate.
• Make sure that your PSU can provide at least the minimum power required by your system. See the table below for details.

So it looks like as long as you're not using two gfx cards you'll be ok!

ASUS A8N-SLI SE Manual wrote:
Power supply requirements
Loading Components/Peripherals Heavy Normal Light
AMD® K8 939-pin CPU type Athlon 64 FX-55 Athlon 64 3800+ Athlon 64 3400+
PCIe™ x16 graphics cards 6800 Ultra x2 6800GT x2 6600GT x2
DDR DIMMs 4 2 2
HDD 4 2 2
Optical drive (DVD/CD-RW) 2 2 1
PCIe™ x 1 card 1 0 0
PCI cards 3 2 1
USB devices 6 4 3
Required +12V current > 25A > 20A > 17A
Required wattage >= 500W >= 400W >= 350W

For reference
Oh and the manual is [url=http://dlsvr02.asus.com/pub/ASUS/mb/socket939/A8N-SLI%20SE/e2252_A8N-SLI_SE.pdf]HERE. (5.5Mb)

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DVdoctor
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Joined: Apr 1 1999

It might be worth also looking at
http://www.slizone.com/object/slizone2_build.html#certified_powersupplies

In addition John ran into a problem with maxtor large drives, it seems that the maxtor drives need quite a bit of current on startup. In a totally different application we were able to solve the problem by adding a 16 volt 2200uf cap across the 12 volt supply but that was for a very specific implimentation on an audio recording system

Sharyn