Very strange motherboard problem. What happened?

[KillrBuckeye]

The problem occurred with my Asus A8N-SLI Deluxe rig in sig. Everything was running fine for a while, but I started getting a random "System Failed VGA Test" on bootup. This morning, I decided to let the computer sit there for a while after receiving this error, and it eventually booted to Windows with no video signal! I could hear the Windows start-up sound and my Raptor working hard. Here's where things get very strange, and I was freaking out thinking that my motherboard was dead.

When I rebooted the computer after this incident, I could immediately tell something was very fishy. From the Windows XP splash screen, less than one full scroll of the progress bar had passed when Windows loaded. Normally, this takes 3-4 full scrolls while it loads all my drivers and such. Anyhow, once Windows loaded, my virus scanner (Avast) failed to start up automatically like it usually does, and I had no internet connection. When I tried to access "Control Panel" => "System", it didn't open up for a full 2 minutes after double-clicking on it. According to the Device Manager, everything was okay EXCEPT the Marvell Yukon LAN controller. However, I only use the nForce LAN controller, and according to device manager it was working fine and had an IP address assigned to it. I have always had both of these LAN controllers enabled in the BIOS, but only used the nForce LAN. This worked fine for weeks.

Not convinced that this was a hardware problem, but rather a problem with my Windows installation, I used Acronis True Image to restore an image of a squeaky clean freshly-installed Windows partition (with the nForce drivers installed). However, to my horror, the system behavior was EXACTLY the same. Seemingly incomplete Windows loading, no internet connection despite the controller being reported OK with an IP address and LAN cable detected, and unresponsive "System" properties dialog. At this point I knew I had a hardware problem on my hands, because this image of my Windows partition should have worked flawlessly.

I then cleared the RTC on the motherboard, changed the necessary on-board device configurations, set the boot device priority, and left all CPU/memory settings at stock. Upon rebooting, the problem was not solved. Finally, I decided to try disabling the Yukon LAN controller (which I was not using) in the BIOS setup. I rebooted, and, VOILA, everything seems functional again, at least with this fresh image of Windows installed. I am restoring a more recent image now and will test it when I get home from work.

It all seems obvious to me now that I should have immediately disabled the Yukon LAN controller when I started having problems, but you know how it takes time to gain a broad enough perspective of the problem to determine what might be reasonable solutions. Besides, I had been using this system for weeks without issues while having both LAN controllers enabled!

My questions are as follows:
- What, specifically, caused this strange system behavior? It seemed to be related to a conflict between the two on-board LAN controllers, but I don't know much about this stuff. Is this related to IRQs or something?

- Why, after weeks of normal operation, did the two LAN controllers suddenly decide to not get along? It's obvious related to the computer booting up despite the VGA error (see first paragraph).

- Why did the motherboard continue the boot sequence after encountering the "System failed VGA test"?! It seems like only trouble could result from this.

Sorry for the long post, but these questions are lingering in my mind and bothering me.

 

[KillrBuckeye]

symptoms described do not support LAN conflict as sole error mode ... is the Yukon working?

Any recent hardware, software, or operational changes?
Any recent power failures or excursions?
Does the video card test "good" in another mobo?

Back in the ASRock thread, you mentioned, in passing, miswiring power to a mobo ... this one?

I haven't tried using the Yukon, but I've verified that the nForce LAN (along with everything else) works fine as long as the Yukon is disabled. No, there was no miswiring with this system, but you have a good memory--that happened with my A8V Deluxe board .

However, there have been a couple unusual occurrences. Last week my wife and I were trying to figure out why our electricity usage was unbelievably high the previous month. We went to the circuit breaker box and flipped individual circuits on and off while one of us was monitoring the meter. My computer was turned off while doing this, of course, but the power cord was still attached. I have a UPS which supposedly has surge protection as well as automatic voltage regulation, but do you think it's possible that flipping the breaker caused power surges that may have made it into the computer despite the UPS? That might explain why I started getting funny behavior, but I can't be certain.

The other thing is that my 3-year old IDE hard drive started acting funny. Even before the circuit breaker episode, it was acting strange. When accessed in Windows Explorer, it would sometimes take 30-60 seconds to respond. When I booted up the computer after the playing around with the circuit breaker, it threw a S.M.A.R.T. error, and sure enough it was dying. I was able to get most of my data transferred from it, but certain files couldn't be read. I can't be sure whether it was dying before the circuit breaker incident, because I hadn't rebooted my computer in several days. The same holds true for the funny VGA error problem--I have no way of knowing whether the issue started just after the circuit breaker incident, or days before.

The funny behavior I described in this thread started only this morning (the circuit breaker incident was a week ago), and only after the machine booted with no video. Another thing of note is that the random VGA errors seemed to have ceased after clearing the RTC this morning, although I haven't tested thoroughly.

There are so many variables involved here that it's tough to draw conclusions. I guess I was hoping that someone had experienced symptoms like this before, and would have an idea of the causes. I really don't want to believe that the board got screwed up by a power surge, but I guess it's possible. However, as of 9:00 am this morning, I believed I had fixed the problem by disabling the Yukon LAN. When I go home shortly, I hope to find a working computer. Thanks for your input.