PSU 20-pin or 24-pin??

Laxe

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Sep 7, 2005
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Hi guys, I'm currently looking to do a major overhaul of my rig and am looking to fit it with either a Gigabyte GA-8I945P Pro mobo or an Abit AN8 Ultra SKT939 NF4.

Now I've been looking for a new psu too and came across something which made me think whether these boards require a 20-pin psu or a 24-pin one? I've looked on the Gigabyte website but it doesn't state that info. Would it really matter or do all the new PCI-E boards need 24-pins these days?

Laxe
 

jnv11

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Jul 19, 2005
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That is wrong. You you will not find any PCI Express boards with only a 20 pin connector because PCIe was designed to deliver the additional power that its designers anticipated were needed by future mainstream graphics cards. That 6 pin connector is a way to supply the graphics card with up to 18 amps (or 216 watts) of additional power if the additional pins in the 24 pin connector are not enough.

You should nowadays avoid any 20 pin power supplies because you could cause a meltdown if you use a 20 to 24 pin adapter, and you can only safely downconvert a 24 pin plug to a 20 pin plug. It is dangerous to upconvert a 20 pin plug to a 24 pin plug because each pin can only carry 6 amps without overheating, and that tying two pins on the 24 pin plug on the adaptor to one pin on the 20 pin plug is just asking for the motherboard to demand up to 12 amps on the pin which is tied to two pins in the adaptor, causing a meltdown.
 

jnv11

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I never said that no AGP based boards have 24 pin plugs. These boards have enough components that they need the 24 pin plugs to deliver the current they need. The 24 pin plug was originally meant to power workstations. Now that even mainstream motherboards with PCI Express need all that power, the ATX form factor replaced its original 20 pin plug with the EPS12V 24 pin plug.
 

knownalien

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does the 6 pin plug have an adapter to a molex?

K8T NeoFIS2R
Athlon 64bit 3400
2X256 Corsaire
Maxtor 40, 120
Western Digital Raptor 74 Gig
ATI AIW Radeon 9700 Pro
NEC LCD Monitor 1760NX
Antec Tru Power 550
Windows XP
 

jp182

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my MSI k8n Neo4 board has a 24 pin slot but it says the manual says you can plug a 20 pin into it. I did and my system is running but i'm getting stability issues, could that be the reason why?
 

Crashman

Polypheme
Former Staff
Wusy, actually it does have a little to do with PCI-E. 24-pin power was carried over to ATX from EPS because the PCIe x16 slots are able to provide more current than AGP slots.

That's also why most SLI boards have another 4 pin Molex near the PCIe slots for adding even more power with a second card.

But 24-pin is not often needed. It's there "just in case". And AGP with 24-pin is kind of silly then, isn't it?

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