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VX450W doesn't like DFI Ultra-D NF4s??


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Similar to an earlier post below, the PSU will spin the fans for 2 seconds but the mobo doesn't power up. The debug lights flash red & go off.


I bought 2 of these PSUs on the same day about a month ago. The first PSU worked for a day before it failed. It was removed and reinstalled into an identical machine with a more powerful video card. Miraculously it still works.


Can't be said for the second PSU, other than it did work for maybe 2 days in my HTPC, which is also DFI Ultra-D based. I have yet another spare DFI U-D & tried it there &, drumroll.. it failed to powerup. Both mobos were tested with an Enermax 550W 20-pin PSU & tested ok, so it is clearly a PSU problem. 2 out of 3 DFI Ultra-D NF4s won't work with either PSU. :thumbdn:


THE SYMPTOMS ARE EXACTLY THE SAME so it is a manufacture fault of some kind.


Warning to anyone buying these VX series PSUs. DON'T buy one if you intend it to be used in DFI NF4 mobos (edit!! it's not the mobo, there are many other platforms with this issue). It may work for a short while, but don't be surprised if it won't powerup one day, or in my case, the very next day.


Any input would be greatly appreciated.

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I just read that perhaps the PCs will not start due to the machine being too small on power? There are 2 case fans including CPU fan attached.


This may explain why I managed to get one working. The system uses a 7900GT with PCIe power where the original PC used a 8600GT which doesn't use external power.


How do you define 'jumpstarting'?

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Jumpstarting how-to:



The issue of high efficiency psu's not booting low power systems should no longer pose a problem.




Since these psu's are able to power up with a couple of case fans attached it should be clear that your issue is an isolated one at best. The VX450 is based on the Seasonic S12-II platform. My HX520 is based on the Seasonic M12, and over the past 6+ months it's been powering my DFI NF4-Ultra D rig 24/7. At one point I was using a passive cooled 7950GT and a single hdd.

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Thanks for clearing up the info on the PSUs actual make.


It won't powerup with extra case fans, the only way it will work is with a more powerful video card. The 8600GT won't start but the 7900GT works fine.


Both fans, including 1 Delta EHE with a decent power draw, are hooked up via the power supply molex, not the 3-pin header. Since the board is not powering up, the fans don't 'half-spin' if the fans are plugged in directly to the motherboard. It is a PSU circuitry problem, & from what I've gathered from the SilentPC thread, the PSU needs to draw a specific amount of power from the 12v rail directly from the PSU's 4-pin molex or PCIe plug.


I am not alone with this. There are other threads here with exactly the same problem as me, not only people with Socket A, 478 & 939 but also a Core 2 E2180 system with a brand new GA P35-DS4 motherboard. This problem clearly still exists and action is required immediately.


Later today I'll go to my bro's place, grab my 7900GT from there & try it with this 2nd problematic PSU. If the PC starts, it will prove that a VX450W requires a PCIe powered video card to work. Adding other components, like extra HDDs, fans & DVDRWs will hopefully prove to be unnecessary. If only I had an 8600GT & PCIe powered 8600GTS.

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