EA-500D boots one PC but not the other

[PCBONEZ]

Re: EA-500D boots one PC but not the other

EA-500D Green has 22 amps on each +12v rail.

Radeon HD 4850 TDP is 114 watts and if we assume a mediocre regulator efficiency of 75% that's 152 watts at the PSU.
If it all pulls off +12v that's 12.7 amps.

HHD's are roughly 1 amp /@ on +12v and a burner up to about 2 amps so that's another +5 amps.

Lets say maybe 3 amps for CPU+System fans...

.... So you're up to around 20.7 amps on the non-CPU +12v rail.

If you are sporting a RAID card that could be tapping a few more amps and I've seen some newer mobos that power RAM [except in standby] from +12v with a VRM dedicated to RAM.

If you have all of that on one rail you just might be over the 22 amps, especially while drives are spinning up.

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TDP on a i5-750 is 95 watts so [w/VRM effiecency] it's probably about 127 watts [10.6 amps]

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Try the system with no hard drives connected.
If PSU stays on, then do some rewiring and move the +12v to the HDDs to the other rail.

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[mockingbird]

Re: EA-500D boots one PC but not the other

That's stretching it, I don't think that's the problem.

[PCBONEZ]

Re: EA-500D boots one PC but not the other

I know older PSUs had some sort of -5V or something that is missing on new PSUs.

Maybe the board needs that?

-5v was for the ISA BUS which pretty much went away with ISA slots.

MSI was using 16-bit chips directly on the mobo through an internal ISA BUS on boards with no ISA slots for a while as a means to 'cost down' their boards but that stopped about the time i845 chipset did the went part of came and went. They used the cheaper 16-bit chips for sound and/or LAN. [That's why some early MSI P4 boards need -5v for full function even though they have no ISA slot.]

MSI might not be the only one that did that trick but they are the only one I know for sure did.
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[PCBONEZ]

Re: EA-500D boots one PC but not the other

That's stretching it, I don't think that's the problem.

No that isn't stretching it at all.
Only 22 amps with a 'big' video card and a slew of drives is pushing it.

- Except I got the problem backwards..
It's the lower powered board the 500-watt won't work with.

I'm stumped.
I don't like to be stumped..
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[PCBONEZ]

Re: EA-500D boots one PC but not the other

Have you tried the 650w [or some other PSU] on the older board since the time it wouldn't stay running with the 500w - and it ran??
Maybe in handling you developed a chassis ground somewhere.

[mockingbird]

Re: EA-500D boots one PC but not the other

Like we agreed before, probably some lousy caps inside the Antec. He said he had the new "Green" edition. Last I checked that thing was full of substandard Taiwanese parts.

[PCBONEZ]

Re: EA-500D boots one PC but not the other

That doesn't explain why it works fine on the more power hungry motherboard.
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[DOS-man]

Re: EA-500D boots one PC but not the other

Yeah, I have the old setup running off the 650 right now, no problem at all. I've been swapping the 500 and the 650 in and out to test. Also, I pulled out the RAM and vid card. Even powering only the processor and the mobo, it still doesn't work.

[mockingbird]

Re: EA-500D boots one PC but not the other

That doesn't explain why it works fine on the more power hungry motherboard..

Different motherboards have different initial power draws and the like... It could be that the motherboard where this PSU doesn't work is exploiting some weakness in the PSU caused by the defect which is causing some failsafe mechanism in the PSU to kick in.

The only other explanation is some flaw in its design.

[PCBONEZ]

Re: EA-500D boots one PC but not the other

That's stretching it, I don't think that's the problem.

[DOS-man]

Re: EA-500D boots one PC but not the other

I've got a cheap multimeter, anything I could test?

[PCBONEZ]

Re: EA-500D boots one PC but not the other

This is really an odd problem. Not sure where to start...

Perhaps check voltages on both PSU's [on old mobo] while it's trying to boot to see which is different.

How [or are] the PSU's mounted when testing the old board?
Is it in the case or off to the side?
And,, how is the mounting different from new to old system.
- I'm looking for grounding issues/situations that are different between the two set-ups.
.. Maybe the 500w has [or lacks] an internal ground that interacts with the mounting situation somehow...
[I may not have worded that well but I think you'll get it...]
.

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[DOS-man]

Re: EA-500D boots one PC but not the other

I've tried it both fully installed (screwed in), and sitting outside the case, it makes no difference. I also pulled the mobo and put it back in, just in case something might have gotten loose or was causing a short or ground I could not see, but that did not change anything either. I'll check the voltages tomorrow and see if I can find anything.

[DOS-man]

Re: EA-500D boots one PC but not the other

Well, I tried getting voltage measurements, but it shuts down so quickly that it's very difficult. I think I'm just going to use the 650 with this mobo going forward. Even if I can figure out why this is happening, I don't see how that leads to a solution.

Hate to throw in the towel, but since I've got a working solution, I think I'll call it good. May revisit it later if I feel like it. Thank you for taking the time to assist me with this.