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Multiple PSU Question

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August 1, 2002 9:58:41 PM

I'm working on designs for a SFF computer to use in house and for my son to use for LAN parties. One of my designs would require the use of a 1U rackmount PSU due to space restrictions. The highest output unit I've found is a 300 watt Sparkle w/ 2 fans. Because of case design I have the option of adding a second 1U PSU. What type of configuration should I use if I add the second PSU. 1. Make it so I can switch from 1 supply to the other. 2. Split the components between the 2 PSUs ie: Mobo on one, hard drives and cd drives on the other 3. Find a way to wire them so that their outputs are combined (I don't know if this can or should be done) Current design configuration would include 2 Maxtor 133 HDD, CD/RW, DVD/ROM, OC'd GForce 4200, and micro-ATX Mobo either nForce2 or Sis 648 based. I'd like to OC them a bit and felt that given the configuration the second power supply would come in handy. Any input/advice would be appreciated.

More about : multiple psu question

August 3, 2002 4:11:00 AM

All Micro-ATX motherboards have been designed to work well with SFF PSU's and subsequently low watt ratings. That 300W should be enough for you. If you did use 2 PSU's you should separate them. There is no way to combine them.

I've never seen anyone overclock a SFF computer but you can try. I'd image you'd run into lots of stability problems however because Micro-ATX mainboards are just not meant to be put under that kind of stress. Overclocking requires a lot of extra power regulation and equal lead lengths on motherboards for the overclock to be stable. And on a Micro-ATX, you just don't have enough real estate to plant all of that voltage regulation gear on it. Perhaps you can OC your Geforce4 ti 4200 but don't count on overclocking your RAM or FSB.

Your 2 maxtor's get to be about 46 C each and the sides of the drive get very hot too. Be careful in a SFF computer that they get enough ventillation, as 55 C is the maximum that Maxtor and most hard drive vendors recommend. The 2 Maxtors should consume about 50W on bootup as well and then average 15-30W while in use, so keep that in mind. Still, 300W should be more than enough. An AMD AthlonXP 2200+ should consume about 60-65W. But try not to be too ambitious. Two hard drives may not even fit into a SFF computer very well. If you are moving this computer around it has to be sturdy and you don't want anything squeezed in. I'd get a shim for your processor if you're moving it around a lot.

There was an article linked from here recently where a guy built a SFF computer using a Pentium 4 1.6Ghz and Geforce4 MX440 using only an 85W PSU. So again, I doubt you'll need more than 300W. Just remember: don't OC your FSB or memory or you will most certainly run into stability issues or your computer may not even boot up (requiring a CMOS clear to restart), make sure you get enough ventillation for your hard drives, and be wary of noise. You may be creating a computer that will be very loud. Hard drives are one of the largest sources of all computer noise. People think it's the fans but it's the hard drives due to sound pressure being transferred very well from them to the rest of the case. Actually come to think of it I would ditch the second hard drive (loading a counter-strike level in 10 seconds compared to 15 seconds isn't worth it) and I would not overclock my GF4 Ti4200. I might underclock it even. When you build a SFF computer you are giving up lots of overclocking possibilities for the sake of having a smaller case. It's not just a smaller case, it's smaller components too.

Last but not least, expect to spend more money after you finish building it to fix it up, tweak it, and reduce noise levels. It's never an easy thing to build a SFF computer, and for most people, it takes weeks of planning, tweaking, and buying lots more things than they thought they'd ever need. Even the Lian-Li 9300 SFF or Coolermaster case won't make building the computer easier for you.

I'm not trying to discourage you, but I'm trying to tell you the truth. There is no easy way to build a good SFF computer that doesn't overheat, and practically none of them overclock very well.
August 6, 2002 6:07:36 PM

Thanks for the feed back, I've been planning this project for a couple of monthes now and feel like I'm closing in on the final design. Glad to hear that I might get away with 1 PSU to start with as I was planning on adding the second HDD and PSU in a few monthes once I got the basic set-up working. I'm planning on using the Maxtor drives with the liquid bearings as they are reported to be very very quiet. As to the OC'ing, I've read that Asus' P4B533-VM based on i845G chip is overclockable, I'm sure there are many that are'nt though, got my fingers crossed regarding micro nForce2 and SiS648 boards, still a few more weeks to wait for the reviews. Gigabyte has a micro on their web page based on SiS 645DX called GA-8STML nobody carries this board though so I guess that ones off the list.
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