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480 GTX PSU related problem

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June 20, 2010 7:07:01 PM

After three and a half years of impeccable service, my faithful XFX 880 GTX finally passed away. So, I had to go shopping. As I tend to buy top end components, in order to offer myself some three or four years of upgrade-free gaming, I decided to go for the new 480 GTX. Naturally, I had to buy a new PSU as well, ‘cause my old 500W unit couldn’t cope with the new video card. I got the 630W Nexus NX-6000 R3.
The rest of the system was built (in time) around a LGA 775 Asus P5K mainboard, the Intel Q9650 CPU (@ 3.0 GHz, no OC), 4 GB of Mushkin memory (two modules), two DVD drives and two SATA hard disks.
The problem is that the system won’t start anymore. The CPU and case fans are starting to rotate for maybe half a second, then nothing. The green LED on the mainboard stays on, but the computer remains off.
Putting the old PSU back on again, the system starts normally, I can see the BIOS screen, but Windows would load, due to a failure to detect the hard drives (there is not enough power for them, I think, because of the new and hungry video card). Nevertheless, the computer at least tries to boot, while the new PSU wouldn’t even move the fans and turn on the display.
I tried to install the old 8800 GTX (it would still work, in 640x480 and 4 bit color depth, with lots of artifacts, even in the BIOS screen). The old PSU works just fine, the new one doesn’t. Same thing: the fans start rotating for a split second, then everything goes quiet. I even tried to put in a very, very old ATI X800, which needs no PCI-Express dedicated power supply and uses a passive cooling system. Same thing.
One more thing that could be important. When I changed sides and came to the Intel camp (two years ago, using the same mainboard I have now), I noticed something strange: after disconnecting the power source completely, using the mechanical switch on the PSU, and then powering the computer again (immediately or the next day, it didn’t matter), the system would start in a two-step fashion: first, the fans would start rotating for a second or so, then the system would stop completely, only to go back on, on it’s self, just a couple of second later. I wondered what could have happened, as this was not something I experienced using my old AMD platform. On the other hand, when the PSU was left on, after turning the computer off, it would start again normally, using the power-on button on the case (I mean, without the short 2 second “break”, before the display went on). Anyway, after trying to find an explanation to all this, searching the Internet and finding nothing, I just quit looking, as my computer worked just fine and the little power-off thing didn’t bother me after all. I just forgot about it, for the past couple of years. Until now. I really don’t know if this has something to do with my current problem, but I wanted to make sure you guys see the whole picture.
I think the user’s manual of my old 8800GTX stated that the two separate PCI-Express power plugs had to come from separate 12V rails, if I remember correctly. In the 480GTX’s case, Gigabyte doesn’t say anything about this, except for the minimum recommended PSU wattage, which should be 600W. I didn’t find anything on the 12V rail AMP requirements.
So, could my new PSU be simply defective? I didn’t have time to mount it in a different computer, to check if it works or not. Could 630W not be enough? Well, in this case, how come the old 500W PSU allows the system to power up, at least until it comes to the stage of detecting the hard drives?
In this moment, just to be able to write this, I left my old PSU do it’s job, using the ATI X800 as the system’s video card.
Sorry for the long post, but I wanted to provide as much information as possible.
Thank you!


June 20, 2010 7:29:13 PM

Sorry for some language mistakes in my original post. I reviewed it after posting and the site doesn't allow me to edit. So, this is what I meant:

"After three and a half years of impeccable service, my faithful XFX 8800 GTX finally passed away. So, I had to go shopping. As I tend to buy top end components, in order to offer myself some three or four years of upgrade-free gaming, I decided to go for the new 480 GTX. Naturally, I had to buy a new PSU as well, ‘cause my old 500W unit couldn’t cope with the new video card. I got the 630W Nexus NX-6000 R3.
The rest of the system was built (in time) around a LGA 775 Asus P5K mainboard, the Intel Q9650 CPU (@ 3.0 GHz, no OC), 4 GB of Mushkin memory (two modules), two DVD drives and two SATA hard disks.
The problem is that the system won’t start anymore. The CPU and case fans are starting to rotate for maybe half a second, then nothing. The green LED on the mainboard stays on, but the computer remains off.
Putting the old PSU back on again, the system starts normally, I can see the BIOS screen, but Windows wouldn't load, due to a failure to detect the hard drives (there is not enough power for them, I think, because of the new and hungry video card). Nevertheless, the computer at least tries to boot, while the new PSU wouldn’t even move the fans and turn on the display.
I tried to install the old 8800 GTX (it would still work, in 640x480 and 4 bit color depth, with lots of artifacts, even in the BIOS screen). The old PSU works just fine, the new one doesn’t. Same thing: the fans start rotating for a split second, then everything goes quiet. I even tried to put in a very, very old ATI X800, which needs no PCI-Express dedicated power supply and uses a passive cooling system. Same thing.
One more thing that could be important. When I changed sides and came to the Intel camp (two years ago, using the same mainboard I have now), I noticed something strange: after disconnecting the power source completely, using the mechanical switch on the PSU, and then powering the computer again (immediately or the next day, it didn’t matter), the system would start in a two-step fashion: first, the fans would start rotating for a second or so, then the system would stop completely, only to go back on, by it’s self, just a couple of seconds later. I wondered what could have happened, as this was not something I experienced using my old AMD platform. On the other hand, when the PSU was left on, after turning the computer off, it would start again normally, simply by pressing the power-on button on the case (I mean, without the short 2 second “break”, before the display went on). Anyway, after trying to find an explanation to all this, searching the Internet and finding nothing, I just quit looking, as my computer worked just fine and the little power-off thing didn’t bother me after all. I just forgot about it, for the past couple of years. Until now. I really don’t know if this has anything to do with my current problem, but I wanted to make sure you guys see the whole picture.
I think the user’s manual of my old 8800GTX stated that the two separate PCI-Express power plugs had to come from separate 12V rails, if I remember correctly. In the 480GTX’s case, Gigabyte doesn’t say anything about this, except for the minimum recommended PSU wattage, which should be 600W. I didn’t find anything on the 12V rail AMP requirements.
So, could my new PSU be simply defective? I didn’t have time to mount it in a different computer, to check if it works or not. Could 630W not be enough? Well, in this case, how come the old 500W PSU allows the system to power up, at least until it comes to the stage of detecting the hard drives?
In this moment, just to be able to write this, I left my old PSU do it’s job, using the ATI X800 as the system’s video card.
Sorry for the long post, but I wanted to provide as much information as possible.
Thank you!
June 21, 2010 6:50:56 PM

Hi, I just tested the PSU on another system. An old one. It works (unfortunately). I hoped it wouldn't work, so I could send it back, with no second thoughts. On the other hand, comparing the different AMP specifications on the two PSUs I have, I found that the new one is weaker as far as +5V and +3.3V are concerned.
Akasa 500W: +3.3V ---- 30A; +5V ---- 30A; +5Vsb ---- 3A
Nexus 630W: +3.3V ---- 24A; +5V ---- 24A; +5Vsb ---- 2.5A
Could my mainboard require more amps on those voltages to start? I don't know, maybe this is a stupid thing to say, correct me if I'm wrong.
Thanks again.
Related resources
June 23, 2010 5:39:47 PM

Hi again.
I started from scratch, checking each contact one by one and making sure they were as tight as possible. And... the system simply took off. I think the problem was related to some mechanical contacts after all.
Thanks again for replying.
End of thread.
August 3, 2010 10:47:46 PM

Hello, I have the same problem with NX-6000 and P5K. I have exactly the same symptons - half a second rotation of fans and then dead. No matter how carefully I plug-in all the connectors, it does not help. Was it really a problem of bad connection or did you need to do anything else? Any other tips? Thanks a lot!
August 9, 2010 6:03:26 PM

Sorry, but I have no clue. Of course, in my case, I was lucky enough to finally get the system started. And I don't see any logic in this other than a faulty electrical contact.
a c 122 B Homebuilt system
August 9, 2010 6:11:04 PM

josef, you should start your own thread. Include a description of the problem and your system configuration.
!