Will this PSU support a 9800GT?
- Thread starter Dazzeerr
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Okedokey
Well-Known Member
ceewi1
VIP Member
I've been off the forum recently, and I hate to miss a good PSU argument, so let me chime in with my 2c worth even though I'm a little late. 
To give a few examples:
PSU1 has +12V1@18A, +12V2@18A, total +12V@36A. If our CPU required 10A, that would leave 26A available for the rest of the system, however not all of that 26A can be used - if more than 18A is drawn from the other rail, OCP will be triggered and the PSU will shut down. 26-18 = 8A is therefore 'trapped' and cannot be used. While there are a few designs like this, they are very much in the minority.
PSU2 has +12V1@18A, +12V2@18A, total +12V@30A. If, again, our CPU required 10A that would leave 20A available for the rest of the system. Up to 18A can be drawn, leaving 20-18 = 2A 'trapped'. This is a more common occurrence. Also keep in mind that it would be a really bad idea to load a PSU capable of providing 30A up to 28A even without the dual rail OCP limitation, most PSUs don't take well to being run at those sort of loads for any length of time.
PSU3 has +12V1@18A, +12V2@18A, total +12V@26A. If, once again, our CPU required 10A that would leave 16A available for the rest of the system. This is less than the 18A current limitation so no power is trapped.
PSU4 has +12V1@18A, +12V2@18A, total +12V@18A (variations on this were actually done with very early ATX 2.0 units, 'converting' an ATX1.3 PSU to ATX2.0 specifications by doing little more than separating the wire group to the ATX12V connector and running it through a separate OCP, as this enabled an ATX1.3 PSU to be marketed as an ATX2.0 unit without the cost and time of designing a new unit from scratch). In this example, no matter how much power is being drawn by the CPU, all power is available for the rest of the system. You will, however, never see this on anything resembling a modern PSU.
This used to be a requirement but was changed to Recommended in a more recent revision. See "Power Supply Design Guide for Desktop Platform Form Factors". Revision 1.1 March 2007 - Section 3.5.7. Single rail designs are ATX compliant.
To give a few examples:
PSU1 has +12V1@18A, +12V2@18A, total +12V@36A. If our CPU required 10A, that would leave 26A available for the rest of the system, however not all of that 26A can be used - if more than 18A is drawn from the other rail, OCP will be triggered and the PSU will shut down. 26-18 = 8A is therefore 'trapped' and cannot be used. While there are a few designs like this, they are very much in the minority.
PSU2 has +12V1@18A, +12V2@18A, total +12V@30A. If, again, our CPU required 10A that would leave 20A available for the rest of the system. Up to 18A can be drawn, leaving 20-18 = 2A 'trapped'. This is a more common occurrence. Also keep in mind that it would be a really bad idea to load a PSU capable of providing 30A up to 28A even without the dual rail OCP limitation, most PSUs don't take well to being run at those sort of loads for any length of time.
PSU3 has +12V1@18A, +12V2@18A, total +12V@26A. If, once again, our CPU required 10A that would leave 16A available for the rest of the system. This is less than the 18A current limitation so no power is trapped.
PSU4 has +12V1@18A, +12V2@18A, total +12V@18A (variations on this were actually done with very early ATX 2.0 units, 'converting' an ATX1.3 PSU to ATX2.0 specifications by doing little more than separating the wire group to the ATX12V connector and running it through a separate OCP, as this enabled an ATX1.3 PSU to be marketed as an ATX2.0 unit without the cost and time of designing a new unit from scratch). In this example, no matter how much power is being drawn by the CPU, all power is available for the rest of the system. You will, however, never see this on anything resembling a modern PSU.
ceewi1
VIP Member
Yes, and just to make things even more complicated there are still a lot of units built to that design (i.e. CPU on one +12V rail, everything else the another).
The document is at http://www.formfactors.org/developer\specs\PSU_DG_rev_1_1.pdf
The document is at http://www.formfactors.org/developer\specs\PSU_DG_rev_1_1.pdf
Hey guys I have been following this thread and actually joined this forum because of this thread. I do have a question though...sry 
I plan on getting a 9800gt, e5200, giga EP35, 5 case fans, card reader etc. will this power supply be good enough http://www.kingwin.com/product_pages/abt610mm.asp ... if not can you recommend one for $30ish ?
I plan on getting a 9800gt, e5200, giga EP35, 5 case fans, card reader etc. will this power supply be good enough http://www.kingwin.com/product_pages/abt610mm.asp ... if not can you recommend one for $30ish ?
ZeroWing
New Member
Hey guys I have been following this thread and actually joined this forum because of this thread. I do have a question though...sry
I plan on getting a 9800gt, e5200, giga EP35, 5 case fans, card reader etc. will this power supply be good enough http://www.kingwin.com/product_pages/abt610mm.asp ... if not can you recommend one for $30ish ?
Please dont tell me you only want to spend $30 on one of the most important parts of a computer >.>. I bought a PSU for $40 w/o knowing anything about them. It works when it does but it sometimes completely shut off and I had to use my hand of rage on it to make it obey. Just bought a 750W Corsair PSU and damn is it nice single rail with 60AMPs is insane
. Has a crap load of connectors. Corsair has made me a life buyer. Maybe one of the pros will let you know what to do b/c I am completely inferior to them.
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Please dont tell me you only want to spend $30 on one of the most important parts of a computer >.>. I bought a PSU for $40 w/o knowing anything about them. It works when it does but it sometimes completely shut off and I had to use my hand of rage on it to make it obey. Just bought a 750W Corsair PSU and damn is it nice single rail with 60AMPs is insane
I know...I know $30ish is a very TIGHT budget for a PSU, but isn't this one good enough?
http://www.newegg.com/Product/Product.aspx?Item=N82E16817121041
it's $35 at a local computer store but $50 on Newegg...will it work ?
it's $35 at a local computer store but $50 on Newegg...will it work ?
It'll work, but remember: You get what you pay for.
It'll work, but remember: You get what you pay for.
ok man now you've got me parnoid... this is not a qaulity PSU ? its $50 on Newegg
ok man now you've got me parnoid... this is not a qaulity PSU ? its $50 on Newegg
I don't have any evidence that supports saying it's a bad PSU (and I'm too lazy search for any), but, if you want something that will last, get this and use the promo code. If that's too high, take a look at some of the guides posted by ceewi1 here, and find a quality unit from a well known manufacturer.
Just what I would do.
