20pin - 24pin ATX power supply adapter - Any good?

  • Thread starter Thread starter killerstiff
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killerstiff

Hi,

I'm assembling a computer for the first time, and just had my first
dissappointment. The 420 Watt power supply unit, which came with the
ATX box has 20 pins and doesn't fit the 24 pin slot on the
motherboard.

I did find a possible solution: There are adapters available to
bridge this 4-pin gap, connecting a 20-pin psu to a 24-pin motherboard
socket, but am I running some kind of risk using it? Is the
motherboard going to perform normally and happilly?

I'm on a very tight budget, so I would definitively preffer not to
have to buy a new psu.

Any comments?

Stefan
 
You may also find that the power supply also does not meet the newer
standards for power managment.
The 20 vs 24 pin issue can, as you mentioned, be overcome. I'm suprised that
the PS was sent in this configuration.
All of the newer power supplies we buy have a "split connector" to allow use
with a 20 or 24 pin MBD socket.
 
Hi,

I'm assembling a computer for the first time, and just had my first
dissappointment. The 420 Watt power supply unit, which came with the
ATX box has 20 pins and doesn't fit the 24 pin slot on the
motherboard.

I did find a possible solution: There are adapters available to
bridge this 4-pin gap, connecting a 20-pin psu to a 24-pin motherboard
socket, but am I running some kind of risk using it? Is the
motherboard going to perform normally and happilly?

I'm on a very tight budget, so I would definitively preffer not to
have to buy a new psu.

Any comments?

Stefan
Click to expand...

You don't need an adapter. A 20 pin power supply can plug
into a 24 pin motherboard. The missing four pins are
redundant, and all necessary voltages are on the 20 pins.

One distinguishing feature, is whether the motherboard is
SLI or Crossfire and has two video card slots. If you have
a dual video slot motherboard, and are putting two video
cards in it, that is the time when you should use a real
24 pin power supply.

If the motherboard is a more modest one, with only one
video card, then a 20 pin connector can be used with the
24 pin motherboard. That is because, with one video card,
there isn't enough current draw on +12V on the main
connector, to tax the 20 pin connector pins.

The third picture down on this page, shows how a 20 pin
fits into a 24 pin motherboard. Notice that the locking
tab may not line up well, between the two plastic
shells.

http://www.motherboards.org/articles/guides/1487_4.html

Paul
 
You don't need an adapter. A 20 pin power supply can plug
into a 24 pin motherboard. The missing four pins are
redundant, and all necessary voltages are on the 20 pins.

One distinguishing feature, is whether the motherboard is
SLI or Crossfire and has two video card slots. If you have
a dual video slot motherboard, and are putting two video
cards in it, that is the time when you should use a real
24 pin power supply.

If the motherboard is a more modest one, with only one
video card, then a 20 pin connector can be used with the
24 pin motherboard. That is because, with one video card,
there isn't enough current draw on +12V on the main
connector, to tax the 20 pin connector pins.

The third picture down on this page, shows how a 20 pin
fits into a 24 pin motherboard. Notice that the locking
tab may not line up well, between the two plastic
shells.

http://www.motherboards.org/articles/guides/1487_4.html

Paul
Click to expand...

Thanks Paul

That article is interesting. The board does not support a second
graphics card, but maybe the voltage could be meant for the extra
three pci-ex1 slots. My next logical question is what the adapter in
consideration will actually do. Does it deliver the correct voltages
through redistribution or is it in fact more a kind of passifier to
keep motherboard and owner smuggly smiling because it suspects that no-
one will miss the extra voltages anyway?

Here's the link for the ebay image. (It costs only €1,00)
http://bilder.afterbuy.de/images/48146/ezb2841ct.jpg

Stefan
 
Thanks Paul

That article is interesting. The board does not support a second
graphics card, but maybe the voltage could be meant for the extra
three pci-ex1 slots. My next logical question is what the adapter in
consideration will actually do. Does it deliver the correct voltages
through redistribution or is it in fact more a kind of passifier to
keep motherboard and owner smuggly smiling because it suspects that no-
one will miss the extra voltages anyway?

Here's the link for the ebay image. (It costs only €1,00)
http://bilder.afterbuy.de/images/48146/ezb2841ct.jpg

Stefan
Click to expand...

Well, think of it this way. On the 20 pin end, they'll be stuffing
two wires into the 12V pin on the connector. The pin on the 20 pin
end, still has the full 12V current flowing through it. On the
24 pin end, half the current flows through each of the two 12V
pins.

What that does, is move the potential burn point, back to where the
two 20 pin connector ends meet. In other words, if you used that
adapter, on an SLI motherboard equipped with two video cards, then
up to 8 amps of current flows in the single 12V pin, where the adapter
meets the PSU connector. The connector pin is rated at 6 amps,
so there is the potential for degradation or overheating to
occur.

So the adapter solves no problem, other than moving a potential
burn point, away from the motherboard connector. If there was
any overloading, use of the adapter would mean the motherboard
would not have to be replaced. Just the connector on the PSU,
and on the end of the adapter, would be burned.

Use of the adapter, also adds voltage drop getting to the motherboard.
PSUs have a thinner sense wire added to the 3.3V pin, and that senses
the voltage at the end of the PSU connector. When the 20 pin to
24 pin adapter is added, that adapter prevents the remote sense wire
from doing its job. That means the PSU cannot compensate for the
voltage drop in the adapter wire, and maybe you'd see 3.2V at the
motherboard, rather than 3.3V.

At the current time, PCI Express x1 cards are not too popular.
The majority of designs shipping, are things like bridged
designs with a USB chip and a "PCI Express to PCI" bridge chip.
The total power consumption might be 2W or 3W, and not from the
12V rail.

There are a couple PCI Express x1 video cards, but the GPU used
on those is probably not one of the hot ones.

So, you are right. Technically, you could find some ugly hot
PCI Express x1 cards, and overload the 12V pin on a 20 pin connector.
But such situations are not common enough yet, to be issuing
any warnings. There are hardly any PCI Express x1 cards worth
buying, and their current pricing is a barrier to them being
more popular.

Paul
 
Well, think of it this way. On the 20 pin end, they'll be stuffing
two wires into the 12V pin on the connector. The pin on the 20 pin
end, still has the full 12V current flowing through it. On the
24 pin end, half the current flows through each of the two 12V
pins.

What that does, is move the potential burn point, back to where the
two 20 pin connector ends meet. In other words, if you used that
adapter, on an SLI motherboard equipped with two video cards, then
up to 8 amps of current flows in the single 12V pin, where the adapter
meets the PSU connector. The connector pin is rated at 6 amps,
so there is the potential for degradation or overheating to
occur.

So the adapter solves no problem, other than moving a potential
burn point, away from the motherboard connector. If there was
any overloading, use of the adapter would mean the motherboard
would not have to be replaced. Just the connector on the PSU,
and on the end of the adapter, would be burned.

Use of the adapter, also adds voltage drop getting to the motherboard.
PSUs have a thinner sense wire added to the 3.3V pin, and that senses
the voltage at the end of the PSU connector. When the 20 pin to
24 pin adapter is added, that adapter prevents the remote sense wire
from doing its job. That means the PSU cannot compensate for the
voltage drop in the adapter wire, and maybe you'd see 3.2V at the
motherboard, rather than 3.3V.

At the current time, PCI Express x1 cards are not too popular.
The majority of designs shipping, are things like bridged
designs with a USB chip and a "PCI Express to PCI" bridge chip.
The total power consumption might be 2W or 3W, and not from the
12V rail.

There are a couple PCI Express x1 video cards, but the GPU used
on those is probably not one of the hot ones.

So, you are right. Technically, you could find some ugly hot
PCI Express x1 cards, and overload the 12V pin on a 20 pin connector.
But such situations are not common enough yet, to be issuing
any warnings. There are hardly any PCI Express x1 cards worth
buying, and their current pricing is a barrier to them being
more popular.

Paul
Click to expand...

Hi Paul

Your reply seems very logical to me and at first confirmed my mistrust
towards a quick-fix adaptor. BUT interestingly enough, I found the
PCU on the manufacturer's website and it actually ships with the
adaptor.

This made me order one.

Stefan
 
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