Motherboard & power supply compatibility problem

Yeah, I know it sounds weird, but I have a PC here that is simply not compatible with a brand new Antec power supply. I hooked the PSU up to a different PC and it powered right up w/o incident. I have checked all the voltages output and everything is perfect. The PC not powering up with the Antec works fine with a different PSU. The owner upgraded from a generic 450w (low low low end) to a nice new Antec HCG-620 to power his system (he added a 2nd GTS450 video card for SLI and the old PSU won't power the system). The motherboard is an EVGA 680i SLI (the full model number is 122-CK-NF68-A1). I can remember reading somewhere a long time ago about how some NVidia chipset boards were not compatible with some power supplies; this was back in mid/late 2008. Other than replacing the PSU, does anyone have any suggestions? Thoughts?
:confused

 

This is a strange issue.

First, I'd recheck all your PSU connections to the board, GPU and drives. This sounds overly simple; however I've had two cases in the past year where a connector's clip "clicked" in place but the actual pins were a hair off from making a connection.

Double check the power requirements for the SLI setup with two GTS450 cards. If the second power supply that works is a higher wattage, there's a slight chance a 620 won't be enough.

Can you test the Antec in another PC running SLI or Crossfire? It could be defective (not putting out anywhere near 620 watts). A sign of this might be the Ethernet port lighting up when the PC in question is off but the PC won't fire up.

Finally (unless someone else has a magic bullet), I would check the EVGA forums and/or contact EVGA tech support to get their thoughts - if it is a compatibility issue with the board they might be able to recommend an "approved" PSU that will work.

Hope this helps.

 

The Antec power supply does not power on the system even if there's only a single low-end PC card (like an OLD Geforce4 64mb), but an old generic 300w unit does and a generic 400w powers the system using a single GTS450. I have done all sorts of wiggling of the connectors, unplugged, replugged, tried using extensions on the main 20+4 and 12v 4+4 connectors and still the same result. If the pins in the connectors were off, using the extensions would 'bypass' that issue, and the PSU probably wouldn't connect on other motherboards correctly, but it does, and other systems run fine with the Antec unit. I spoke with EVGA and Antec tech support, and neither company could provide an answer. Both said "Weird - I've never heard of anything like this before". I asked EVGA if a BIOS flash update could possibly solve the problem, he said "I doubt it, but I guess it's worth a try". I flashed the BIOS, no change. I originally thought the issue was due to the lack of a -5v line on the new Antec unit, but the PC powers on using a different unit that also has no -5v line, so that's not it. We're going to order a different brand (a ThermalTake 700w) unless a miracle fix comes along.

 

I think the problem may be "Active PFC" if that makes any sense... we tried another brand new unit (a 700w CoolerMaster Extreme Power) and that didn't work either. The only units that power the board seem to "budget" or "lower end" models that don't have Active PFC. Absolutely crazy.... :banghead The system is running just fine now on a 500w Topower unit that does not have Active PFC.

 

Now that I think back to my days selling PC components a few years ago, I'm remembering how squirrelly many of the EVGA boards were - especially their first generation i7 socket 1366 models. Although I never ran into the power supply issue you're having, I do remember issues with random rebooting and BSODs - most of which were solvable simply by doing an update flash of the BIOS.

Although a longshot, check to see if a BIOS update is available for the motherboard at EVGA's website. I doubt it will hurt and there's a slight chance it may solve the PSU issue.

 

Thanks for the suggestion, but I already tried it.... the only PSUs that would power the board were all lower-end models w/o ActivePFC. That's the only thing we could find different between units that worked, and units that didn't work. After contacting EVGA tech support again today, we told them about our thoughts on the Active PFC 'issue' and they said "we can't believe that it would make any difference" to which we replied "we can't believe that you're telling us that NOBODY has EVER reported this problem before; we can't possibly be the ONLY people to EVER have this issue", to which EVGA replied "we have no record of anyone else having this issue invloving that power supply and that motherboard" which kind of implies that they have heard of the issue but not with these exact components.....

 

My bad. I missed your comment about the BIOS in the previous post. :-o

The biggest lie in the world is "The check is in the mail."

Given the current state of manufacturers' tech support, the second biggest lie in the world has been replaced by "We have no record of anyone else having this issue." :-D

 

dlb, you've probably already done the research, so I won't bore you with explanations about what active vs. passive power factor controlling or compensation means, what it's used for, etc.

Even though you've solved the problem by using a non-PFC supply, if you want to dig further, try this: mount as many hard drives, opticals, discrete devices as you can on the board in question - anything that uses the 12v rail. Then try the Antec and/or the CoolerMaster - you might be surprised at the results.