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PSU 20-pin into a 24-pin ATX Mobo

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Anonymous
a b ) Power supply
September 2, 2008 12:26:17 AM

I have googled this topic for the past hour, reading past forum posts etc. but either some are old topics or they don't apply to my question, in my opinion.

Basically my fuse for my PSU burnt out and instead of replacing the fuse or PSU (both are cheap i know), I bought down an old PC from the loft and took out its PSU. This one is a 350W 16A on the 12V line with a 20-pin ATX connector. I want to ask if I can use it safely on an mobo that has a 20+4-pin socket.

I know it fits so that there are 4 pins left open, which seems to be what all the other forum threads are talking about, but I want to know if it would damage any components if I switch it on. This PC will just be used to open outlook + internet explorer running on winXP, nothing stressful.

The CPU is a Phenom 9500 running at stock speeds, which is quoted as 95W http://products.amd.com/en-us/DesktopCPUDetail.aspx?id=... and there are no pci cards such as sound or graphics and the mobo is an Asus M2A-VM.

I ask this because I thought that the extra 4 pins for the ATX are to run the pci-e slots and if there was a pci-e card installed and a 20-pin supply was used then there would be stability issues and, from what I've read from these other topics I've been talking about, the system would freeze within a few minutes. But on the 10+ forums I've been through, none of them covered the situation with either a quad core or no pci-e card. Therefore I would have thought that for a build such as mine, I could run it stable using only a 20-pin supply since there are minimal components that need power.

I guess this would be true for a single, mid-range core running <3GHz but I don't really know about quad cores, since the 9500 runs at 2.2GHz but the effective clock is x4 that? Does that mean more power concumption? But then the die size is smaller @65nm so it actually uses less power than a typical P4 single core or something. I want to ask here to see if anyone has any experiance or more knowledge about the potential stablity of the system before I just whack in the PSU and turn it on.

As a note...
I know there are 4-pin or molex converters that allow the extra 20+4 to work but I want to stress that this 350W power supply would be very tempory as I need the PC working asap and the time to order and recieve those parts will be too long. Besides, I could do with the knowledge, as well as leaving this thread here for others with similar questions to refer to. I will order a 600+W supply soon with pci-e 6-pin connections since I am looking to buy an 8800gts/x but for now I basically need the advice and go-ahead :)  ... what a long post, sorry!

More about : psu pin pin atx mobo

Anonymous
a b ) Power supply
September 2, 2008 3:04:04 AM

hmm in theroy the PC should switch on and if its not a big system 350W should be ok ish, from what i know AMD love there energy efficeint cpu's

however if you are worried about power i would remove as many Ram Dimms as possible and go into the bios and disable 2 or 3 of the cores and also enable speed step to keep the PC running slower but using less power, then to be extra safe go to the power options in windows and ckick power saver mode like you would for a laptop to keep its life longer

i recon a quad CPU system with 1 hard drive and 1 ram slot with no PCI cards or PCI-E cards, with as little USB devices attached to the PC as possible should be fine it is after all a 350W PSU.

its not an ideal solution using a 20 in a 24 pin however it should work just dont do it for long and buy a new PSU eventually id recomend 500W+ from any decent manufacture that will allow you to put lots of extra bits in ya pc and a midrange GPU if you need one.
Anonymous
a b ) Power supply
September 2, 2008 5:21:17 AM

hmm it uses an USB mouse and its on a LAN. Perhaps its pushing it :/ 
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September 2, 2008 6:24:46 AM

It will work, I have done it before. I would be more worried about the wattage.
September 2, 2008 8:58:46 AM

It will work with onboard graphics. If the PSU is 3 or more years old it will have dropped in peak output due to ageing capacitors, and it could fail due to its age. If its not a good quality brand it could fail and take other parts with it.

Mike.

September 2, 2008 10:34:30 AM

OK to be honest the whole 20 + 4 pin thing is mainly for boards that can run multiple graphics cards. All my multicard motherboard manuals (4 in total) say that the second 4 pin connector is only needed *IF* your using a second pci-e x16 device. So effectively you should be fine if your board is anything like the boards I've dealth with.
Anonymous
a b ) Power supply
September 2, 2008 5:13:38 PM

yeah i guess they are for pci-e cards unless you have a low wattage PSU, in which i think the extra 4 pins would provide stability.
Anonymous
a b ) Power supply
September 4, 2008 12:28:16 AM

u will know when the pc shuts down
!