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Guest
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 Posted: Tue Feb 07, 2006 9:33 pm Post subject: K7S5A mb and ATX 2 psu |
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Bought a Npire ISO-500 450W PSU recently but it doesn't seem to work
with my ECS K7S5A motherboard. Drives power up, CPU fan comes on, but
PC won't boot and no beeps from m/b. I brought it back to the store
where it worked well on another m/b with the separate 12v connector
used. Is this a known incompatibility issue or is there something else
wrong? Any suggestions?
TIA |
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tcsenter
Guest
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| Posted: Tue Feb 07, 2006 10:32 pm Post subject: Re: K7S5A mb and ATX 2 psu |
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Your other rails look OK, but the max current rating on +3.3V rail is
probably insufficient at 22A for an older pre-ATX12V system. Try a PSU
with at least 28A on +3.3V, in line with these NSpire models:
NSP-450P4DL (450W) +5V@40A, +12V@20A, +3.3V@28A
NSP-430P4D (430W) +5V@36A, +12V@20A, +3.3V@28A |
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larry moe 'n curly
Guest
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| Posted: Wed Feb 08, 2006 8:31 am Post subject: Re: K7S5A mb and ATX 2 psu |
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jfroche@gmail.com wrote:
| Quote: | Bought a Npire ISO-500 450W PSU recently but it doesn't seem to work
with my ECS K7S5A motherboard. Drives power up, CPU fan comes on, but
PC won't boot and no beeps from m/b. I brought it back to the store
where it worked well on another m/b with the separate 12v connector
used. Is this a known incompatibility issue or is there something else
wrong? Any suggestions?
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Maybe the voltages are off because the +12V rail isn't being loaded
down enough, especially if the PSU has dual +12V rails. Many PSUs have
minimum as well as maximum amp ratings for each rail and use one of the
rails for overall regulation. If yours is a dual rail system, then
maybe you need to add a load resistor across the square ATX12V
connector, something around 10-20 ohms and 30-15 watts (30 watts for 10
ohms, 15W for 20 ohms). I had this kind of problem with an old PSU
that used the +5.0V rail for overall regulation, and my 500 MHz CPU
didn't draw enough power to make the +3.3V and +12V right (+12V fans
would spin but +12V HD motors would not). |
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Guest
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| Posted: Wed Feb 08, 2006 8:32 pm Post subject: Re: K7S5A mb and ATX 2 psu |
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Nspire technical support have been very helpful by responding quickly
to my emails saying that a) there is no known problem with this PSU/MB
combo and b) that a rail should never have to be capped to get it
working. I'll compare specs later and post them. Thanks. |
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larry moe 'n curly
Guest
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| Posted: Thu Feb 09, 2006 3:32 am Post subject: Re: K7S5A mb and ATX 2 psu |
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jfroche@gmail.com wrote:
| Quote: | Many PSUs have minimum as well as maximum amp ratings
for each rail and use one of the rails for overall regulation.
If yours is a dual rail system, then maybe you need to add a
load resistor across the square ATX12V connector, something
around 10-20 ohms and 30-15 watts (30 watts for 10 ohms,
15W for 20 ohms).
Nspire technical support have been very helpful by responding quickly
to my emails saying that a) there is no known problem with this PSU/MB
combo and b) that a rail should never have to be capped to get it
working.
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If tech support confused capacitors with resistors, then I'd be
skeptical about it.  |
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Guest
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| Posted: Thu Feb 09, 2006 4:31 am Post subject: Re: K7S5A mb and ATX 2 psu |
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The old PSU, HEC-250BR, that works:
+3.3V@16A, +5V@25A, +12V@10A, +5Vsb@2A, -5V@0.5A, -12V@0.8A
Total output 250W, +5V and 3.3VV combined 150W
The new PSU, ISO-500D, that doesn't:
+3.3V@22A, +5V@36A, +12V@18A, +5Vsb@2A, -5V@0.5A, -12V@0.5A
Total output 450W, +5V and 3.3VV combined 220W |
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Guest
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| Posted: Thu Feb 09, 2006 3:32 pm Post subject: Re: K7S5A mb and ATX 2 psu |
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I'd be very sceptical too  but they didn't. |
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JimL
Guest
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| Posted: Fri Feb 10, 2006 12:32 am Post subject: Re: K7S5A mb and ATX 2 psu |
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On 9 Feb 2006 07:14:18 -0800, jfroche@gmail.com wrote:
| Quote: | I'd be very sceptical too but they didn't.
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I had an internal modem that caused a problem.
Also I've had video cards that did that.
In other words, you need to eliminate everyting in the system. Boot
to a floppy with no hard drive, then if that works, ....
You get the idea.
.. |
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larry moe 'n curly
Guest
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| Posted: Fri Feb 10, 2006 5:32 am Post subject: Re: K7S5A mb and ATX 2 psu |
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jfroche@gmail.com wrote:
| Quote: | Nspire technical support have been very helpful by responding quickly
to my emails saying that a) there is no known problem with this PSU/MB
combo and b) that a rail should never have to be [CAPPED] to get it
working.
If tech support confused capacitors with resistors, then I'd be
skeptical about it. ;)
I'd be very sceptical too but they didn't.
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Then I'm confused because each voltage rail is already capped inside
the PSU, and the mobo adds tons more capacitance. |
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Guest
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| Posted: Fri Feb 10, 2006 7:32 pm Post subject: Re: K7S5A mb and ATX 2 psu |
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IME, *capped* means loaded, as distinct from *open*. An open rail
would NOT be capped with a capacitor but with a resistor. |
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larry moe 'n curly
Guest
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| Posted: Sat Feb 11, 2006 12:32 pm Post subject: Re: K7S5A mb and ATX 2 psu |
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jfroche@gmail.com wrote:
| Quote: | Nspire technical support have been very helpful by responding quickly
to my emails saying that a) there is no known problem with this PSU/MB
combo and b) that a rail should never have to be [CAPPED] to get it
working.
If tech support confused capacitors with resistors, then I'd be
skeptical about it. ;)
I'd be very sceptical too but they didn't.
Then I'm confused because each voltage rail is already capped inside
the PSU, and the mobo adds tons more capacitance.
IME, *capped* means loaded, as distinct from *open*. An open rail
would NOT be capped with a capacitor but with a resistor.
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Sounds like that would apply more to plumbing. ;)
People have referred to "capping" their K7S5As because so many of the
capacitors on it have failed prematurely. OTOH when people had
problems with a certain $13 surplus high quality PSU not working, they
were told to "load" it, never to "cap" it. |
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