Dell Optiplex gx520 motherboard upgrade - new motherboard wont boot.

[arkangel11004]

I purchased a Dell Optiplex GX520.
I ordered an Optiplex GX620 motherboard to upgrade the old one because I wanted a PCI-e x16 graphics card.
I put the GX620 motherboard in, and the computer gets power and is able to turn on. However, the fan runs loud and continuously, and the power button (not the AUX power light on the motherboard) stays solid orange. Even though the computer gets power, the system never gets any farther than this. I do not even get a display signal to my monitor, and therefore never get to see the bios (or anything else for that matter). I might have assumed that this was the power supply, except that the old motherboard can be put in and boots up just fine. I have reseated memory, and made sure the processor is in the right orientation. The system, as a matter of fact, even does this when no memory or processor is present. I have disconnected everything and even removed the BIOS battery (a.k.a. CMOS battery I believe). There seems to be no reason for this behavior. I would greatly appreciate any suggestions.

 

[o1die]

The problem is that older oem motherboards have limited bios settings; your old cpu or new video card simply may not work; another reason to build your own. Have you tried your new board without the new video card? What video card are you trying to use?

 

[cl-scott]

As I recall, from my days as a Dell hardware tech, that means that the CPU microcode isn't being executed. There should be a couple of diagnostic LEDs on the case, numbered 1-4, and if any of those are lit, the specific ones will also help pin down the issue. You can compare what you see against the online documentation. I'd just check the codes for the 620, not 520. Not sure they're different, but may as well be safe.

OEM computers, like those from Dell, tend to have very locked down motherboard chipsets. You can't just slap any CPU in them you want and have it work. You get a very narrow range, and that's it.

 

[arkangel11004]

The problem is that older oem motherboards have limited bios settings; your old cpu or new video card simply may not work; another reason to build your own. Have you tried your new board without the new video card? What video card are you trying to use?

I as of yet have not placed the video card in the motherboard. I purchased it from ebay and It was just delivered today. I will pick it up tomorrow. It is this card:

http://www.ebay.com/itm/160815262234?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[arkangel11004]

I Have a Pentium D 2.8ghz dual core processor if it helps. It was supported by the GX520 motherboard.

 

[arkangel11004]

Thank you all for the help. I do not exactly know what i did, but the computer now boots. I cleaned out the contacts everywhere and when i hooked everything up, it booted normally. It may have been that I plugged in the power supply before I put the processor and memory in.

Again, Thanks for all the help,

arkangel11004

 

[arkangel11004]

Best answer selected by arkangel11004.