I posted this on a couple of different forums. I have been researching the problem and tried all of the ideas to fix the problem. My situation is a touch different since I can't get it to POST anymore. I explain more in the thread.

Here it is, I am having some trouble with my M2N-SLi Deluxe. The problem is this, I recently purchased an AMD Phenom 8450 AM2+ to upgrade from my 4200+ X2 AM2. The motherboard (with 4200+) has been bullet proof for a while now and after I tried to install the new processor the computer wouldn't POST, fans would power up and such, and systems seemed normal except nothing would show on the monitor and no beeps/signs from the BIOS. So I took the Phenom out and put in my old 4200+ but it still wouldn't POST. I tried flashing the BIOS with the 4200+ in the computer to at least get it to its original boot settings but that did nothing. I am very discouraged right now, and there is little to no good information out on forums and such. I would greatly appreciate some guidance on this situation. I read that AM2/AM2+ are compatible but require BIOS update. But I am unable to even get the computer on to update the BIOS. I have been using ASUS Motherboard for years now and they have been great to me, I hope you can offer me some assistance, thanks! If you need any extra information just ask. This problem has me baffled, but now I am leaning towards a dead motherboard. Let's hope not!! LMK

I would assume you did this, but worth mentioning just in case, did you reset the BIOS with the jumper?
If you get it to reboot with 4200, the wise thing would be to update the BIOS with lastest version for your board that includes support for the Phenom.....before you install the Phenom.

Yes sir I did reset the BIOS with the jumper. It may be possible that I did it incorrectly. The main issue is that I can't get the computer to post so therefore no way to even update the BIOS for the new processor. I know that I did the install incorrectly in the first place, by putting the Phenom in before I updated, which is causing the problems. I have gone back to the 4200+ and it is still doing the same thing. No POST.

create a bootable floppy on another computer if possible. The manual says to do this to update the bios out of windows.
The manual also says that it is able to flash the BIOS DURING the POST.
Beyond that, Ive got no other help.
I'm using a M2n-SLI DEluxe, and I've already updated the BIOS to 1404.

Would the floppy allow the update even if the computer isn't POSTing? You say during the POST, which to me means it would need to be POSTing for that to work. I am only hesitant and haven't tried this yet since getting a floppy A. with an updated BIOS and B. Into my computer with no floppy drive would be lets say, frustrating. But if nothing else works I suppose I don't know what to do.

This problem is absolutely haunting me right now. I have no idea what to do, and it sounds like people have this similar problem but they are able to throw an AM2 chip back in it to get it to start up. I do that an i still have no POST.

Well, I can't seem to find an answer. I'm sure there are others out there with this problem so I will update quickly on what I have done and what I intend to do. After the original problem I tried everything, new processors, 0-4 sticks of memory, nothing on the board, only the processor, I tried everything, never gave me a POST, so I'm going to put my MOBO as dead. I will be buying a new AM2+ motherboard on my way home from work today, is there any procedure that you may suggest for switching out a motherboard?

These are the steps I am going to take.

1. Install MOBO with processor. Check to see if it POSTs.
2. Assuming it POSTs then I will complete the hardware install. I am going to do a short install (VGA, Proccessor, HDD, CD-ROM, Memory) Basically I am leaving my wireless NIC and TV tuner out for now.
3. Upon start up I will enter BIOS, check date, and change my boot squence to 1. CD-ROM 2. HDD
4. Instert Windows XP installation CD before restarting.
5. Save BIOS settings and restart.
6. Enter Windows XP install (Pressing Enter when prompted, not going directly to the repair option)
7. Select my OS Install and hit R.
8. After that it may differ a touch, installing drivers, service packs and such.

If anyone sees ANYTHING wrong with this list, please POST (unlike my motherboard). Thanks for all of your help.

I have this same mobo and put a 9500 in it from an older x2 5200. I can tell you that when I tried to upgrade the bios with the old chip in it, it would not POST. I also attempted to jumper to reset and it still didn't post. The only thing that got it to work with the old x2 chip was take the cmos battery out for about 5 minutes (regardless of the jumper position). Once I put the battery back in, it posted. Also disconnect the power when you do this so it has no energy whatsoever.

After you posted on the old chip, I'd download the 1502 bios from asus and EZ2 flash it (i'd pull the battery again after just to reset it again). After all that is done, you can pop in your phenom.

try these step to get your board to post.

unplug the pc.
take the cmos battery out.
press and hold the power button for 5-10 seconds.
put pc back together and boot.