20/24 pin power plugs for mobo

Zed

Zed

Zed

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Joined
25 Apr 2006
Posts
8
Hi all,

Newby here. I am building up my first machine this weekend.

I have an Arctic Cooling Silentium T2 case with the Seasonic 350w (450w) psu. I am putting in the Asus A8R-MVP mobo. For the record, probably not the best combination if you want to install a FDD or a secondary IDE drive as these are blocked by a metal HDD holder. However, my SATAII drive seems to fit as the cables are elsewhere. As an aside, I had to use the legacy power (4 pin) as the Arctic SATA power cable does not have the length to reach the HDD power plug.

I have now hit a snag. I have finally managed to put the mobo into the case but I ain't got no power to switch on.

I am including a picture of the mobo from the Asus which you can enlarge. http://uk.asus.com/products4.aspx?modelmenu=2&model=787&l1=3&l2=15&l3=236

I have plugged in a 4 pin 12V power plug into a square plug. On the picture you see it in the top right corner (to the right of the Asus heatsink which is below the pink rectangle)

Now I would have thought that it needs more than this and there is a 24 pin plug at the bottom (labled EATXPWR on the mobo). The problem is the PSU has only a 20 pin plug. Now, after I switched the machine on with only the 12V plug, nothing happened. After unplugging and earthing myself etc, and much wailing and gnashing of teeth, i noticed that the 20 pin PSU plug might fit into the 24 pin mobo plug. It did although obviously 4 pins short.

in the Asus booklet, the 4 pins without a connection is are a +3V, +12V, Ground and +5V. Now, if I have plugged in the 4 pin square power plug mentioned above and this 20 pin into the 24 pin socket, can I switch the machine on. I am wary of doing this until someone tells me "Fine. Go ahead."

I think it might be because of what the Arctic Cooling website says but their English is a little obfuscated. Here is the text:

Does any motherboard need an ATX 2.0 PSU with a 24 pin plug?
For ATX there is no motherboard that requires an ATX 2.0 PSU or a 24 pin plug. If the PSU provides enough continuous power at the 12 Volt rail (as ours), all configurations will work fine. Our PSU is tested with a 3.8 GHz Pentium 4 and a NVIDIA 6800 Ultra VGA board.
Using the 20 pin mainboard plug at mainboards with 24 pin socket you have to install in addition a 5.25" power plug in case there is such a socket (depending to the mainboard manufacturer) to get the power for the VGA board. Don't use a 20 to 24 pin adapter!
To supply the CPU with power the mainboard uses a 4 or 8 pin socket. 4 pins are fine to supply CPUs up to the Intel Pentium D 840. In case of the 8 pin socket, 4 pins will keep empty. Don't use an adapter.

Bolding supplied by moi. It would seem that a 20 pin plug in a 24 pin socket along with the 4 pin 12V plug in the top right corner for the CPU should work. Just trying to prevent a blown mobo before I even start.

Thanks
 
welcome to the boards mate!

dont actually know the answer but personally if it has 24 pins and you dont have 24 pins then if it was me i wouldnt do it.

20 to 24 pin plugs are cheap from an auction site altho i dont think doing that is reccommended either altho i have been doing for a few motnhs now
 
It does seem unclear, what atx version is that psu then?


I have used motherboards that require a 4 pin cpu power connection without any (the psu was really old so 20pin only) It works fine its just not as stable as it would be with one.
It wont overclock so well without the proper power and the 12v rail will look really low, if it runs I can see no harm with that.

Imo you wont damage it by undervolting it
 
Hi guys,

I think I may be able to answer my own question. I downloaded a manual from Artic Cooler and it says this:





.

Now, that probably means nothing to you but that is a .pdf problem. Anyway, it does say that the 20 pin connector can be used on any 24 pin connector but that some manufacturers require a 4 pole powerplug (HDD1-3) to be installed.

OK. Thanks for the the input. BTW Dreadi, they say specifically not to use a 20-24 pin adapter.

Cheers for now. maybe later I can tell anyone interested how to install an Artic Cooler Silencer 64 Ultra TC onto an Asus A8R-MVP mobo. With great difficulty but do-able :D .

Cheers
 
Hi Zed

Today i built my first computer (having some trouble installing Windows but the comp seems fine) and i hit the same snag as you. My Mobo has the 24 pins rather than the old 20. And my PSU had a 20 pin connector. I read through the manual however and it turned out that it was like that so that it was compatible with both. You see, your PSU should come with an additional 4 pin connector, that is the same colour, and slots onto the side of your 20pin connector (little slots attach them together).

At first i couldn't find it because i had shoved it into the CPU slot you mentioned in your post (the 4pin one), but it turns out i had another connector that was for that.

So yeah, i attached the two together to make a 24pin connecter and used that. They were both black btw.

I was using a Tagan PSU and a DFI mobo, so the colour codings may be different.
 
Hello there.

Is there a 4 pin tied to the 20 pin by any chance? If so you connect the 4 pin to the 20 (should just stick in) and then plug in.

I wouldn't advise it, but I can tell you I was running my system for a day or two with the 20 pin in the 24 socket.
 
Morning Ragnaros and Hlebio,

OK, i'll go downstairs and check on whether that 4 pin cpu plug fits in the 20 pin slot. From memory not but it always pays to see. I did turn the machine on though and the lights came on. Now if only i could find the power cable for the damn monitor :confused: .

Seriously, no freaken power cable :mad: . Searched the house up and down for an old kettle one but no luck as we have a cordless at home.

Then tried hooking up the computer to the TV through the Svideo - RCA converter. No luck. Probably requires some sort of software switch which, without a monitor is difficult to do.

As this build goes on, I might have to turn this into the "War and Peace" sized trials and tribulations of a newbie page!
 
the 20 pin plug will be OK in a 24 way socket as they are keyed to only fit together one way, the additional 4 pins are only used provide additional power to ensure stability on some boards.

My Antec Aria PSU only has a 20 pin connector and the instructions with my MSI motherboard say to just connect to the 24 way connector.

As has already been said....if you have the additional 4 way connector this clips to the side of the 20 way plug)

HTH
 
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