Another non-POSTing motherboard

[silverpig]

Old components:

Nvidia 7900 GS
Antec NeoPower 480
Hard drives (74 GB raptor and some other SATA drive)
Other non-important components

New components:

Gigabyte EP45-DS3L
Intel Q6600
2 x 2GB OCZ RAM

Parts taken out:

DFI LanParty NF4-Ultra-D
Opteron 165
2x512 MB Mushkin RAM


The old components worked fine with the old motherboard, cpu, and ram. I just swapped out the mobo, cpu and ram, and the thing won't POST or anything. I have made sure to connect the mobo's power cable and the extra 4-pin power cable, and have plugged in the 6-pin power cable to the video card.

When I switch on the power supply on the back of the case, the computer starts up without pushing the power on switch. It does this even if the case switch isn't connected. All the fans spin up, the 4 LEDs come on (green, green, yellow, red), but I get nothing on the display. I tried single RAM sticks in all slots, re-seated the cpu and heatsink, re-seated the video card, tried it with no RAM, no video card, no RAM or video card, and I get the same thing. Fans on, LEDs on, no beeps, nothing.

Help!

UPDATE

So it's the power supply, but I don't know why. I have an Antec NeoPower 480 which works great for my old DFI board, but when I use it with the new board I just get a high pitched whine from the power supply and it won't supply power to the board. DFI good, Gigabyte no good.

I tried an old Thermaltake 450W power supply and lo and behold, the board boots up, POSTs fine and everything. Why would my NeoPower 480 crap out on this board, but the older crappier power supply work fine?

I don't really want to use the Thermaltake power supply as it only has a 20 pin connector and not a 24 pin.

 

[silverpig]

UPDATE 2

Stupid power supply. I went out and bought a new neopower 550 and the thing works perfectly. My old neopower 480 still works in my old system, but not this new one for some reason.

I guess I'm gonna be selling some parts off here... DFI Ultra-D, Opty 165, 1 GB ram...

 

[Quiksilver]

The old power supply just probably can't take the load of the newer system due to higher power requirement.

Think about it, components of a power supply over time age and cannot put out the same amount of power it could have when it was new. So it may have been about to put out that 480W, when it was new; but for example it can now only put out say 450W.

Also if you take into consideration heat too that amount can become even lower depending on what the capacitors were rated for. So, let's say they are rated for 40C and due to the extra heat of the Q6600 the PSU is now getting as hot as 45C; based on the de-rating curve it loses 1-5W per degree over the rating. So if it were only putting out 450W; factor in the heat it is now between 445W and 425W capable.
***The examples are all just for demonstration; I'm not saying that what the PSU is capable of now.

Now, that Thermaltake as you suggested was able to power the system fine; I don't think system againg played a large role in this but more like the old Neopower was crap. No other way around it and based on some of the older parts in the PC; I take a guess that the PSU was bought back when Antec was still using Fuujyu (screw the spelling) capacitors which were known for failing quite often and were generally crap overall. It was probably a combination of that and heat which lead to problems with the new PC; the coil whine suggests that as well as your putting a larger load on the PSU.

The only thing I wouldn't be able to answer is the turning on without case switch; probably has something to do with the PSU state modes though.

That new Neopower should work just fine though, it's a Seasonic based platform so no bad capacitors and I think it's rated for 50C.