Baffling Intermittent No-POST Problem

I am completely baffled by a strange intermittent problem that has affected my PC in the last 2 weeks. I recently sent my motherboard in for RMA service to ASUS for dead SATA ports. They quickly sent me a new board, which worked fine for about a month...

The issue is that more often than not, the computer will not POST upon powering on. No beep, no num-lock status, nothing. However, basic motherboard functions such as holding power for 5 seconds to shut down still work. When the computer does start, it works great.

Specs:

AMD Phenom 9600 X4 (stock voltage)
4 GB (4x1) OCZ Reaper 8500 DDR Unganged (stock timings 2.2v)
ASUS M4N78 Pro
EVGA Geforce 8800 GTS 640 MB PCI-E
SB Audigy 2 Platinum ZS
5x IDE Hard Drives (2x 160 GB, 250 GB, 500 GB, 1 TB)
Enermax NAXN 550 Watt PSU (Installed yesterday)
Enermax Full-Tower Server Case

Symptoms:

The computer will POST and boot without issues if turning on for the first time in the day. For example, I'm using it now. Power must have been off for a few hours before it works again.

BIOS intermittently displays these random failures: chassis intrusion, cpu fan not spinning, cpu over voltage and no keyboard detected. All of these are false alarms. For the most part when it does boot, none of these warnings are displayed, but sometimes a 'core unleashing failed' is displayed due to an incomplete post.

The computer passed all burn in tests, all memory and hard drive tests and is capable of gaming at 1920x1080p with all graphics maxed for 2 hours straight without crashing. Its as stable as ever once it actually starts.

Troubleshooting so far:

-All power connectors are connected
-Reset all BIOS settings
-Checked seating of all peripherals and memory
-Removed all peripherals from PC, including the 8800 GTS, USB headers, hard drives and all but 1 stick of RAM (tried to boot with each individual stick)
-Re-flashed BIOS to latest version (trying an older version next)
-Replaced 430 Watt Antec power supply with new Enermax 550 Watt
-Tried booting with a third power supply
-Tested levels on both power supplies
-Checked motherboard and CPU voltages and temperatures (all in the green)
-Removed CPU, checked pins, thoroughly cleaned heat sink and die surface reapplied thin layer of thermal compound
-Cleaned all fans, all contacts and conductors
-Removed front panel headers to manually power on (checking for shorts in buttons)
-Removed motherboard, checking for possible shorts or arc-points

At this point I'm almost 100% certain its a bad motherboard. Any idea would be appreciated! I'm a computer tech of 15 years, so please bring on the tech talk.

I started another RMA with ASUS but after 4 days, have heard nothing. I have used ASUS products in my business and have sold their motherboards exclusively for more than 11 years. However, due to the fact that this will be my third RMA on this board, and that the replacement process is far from prompt, I am looking to discontinue all sales of ASUS products. Can anybody recommend a better brand? I have always liked MSI.

Hi Telcart,

I would start with a completely barebones system. Strip the system to only one memory stick (or two if pairs are required) and one HD. No dvd or anything else. If the system is unstable with just this then I would suspect the board. If the board remains stable (in your case posts on every start) then I would introduce each item one at a time until the problem presents itself again. I have used a lot of Asus boards in the past and found them flawless.

Let us know how you get on.


Michael

Random power issues are a common indication of faulty capacitors. Sometimes in the PSU and sometimes on the motherboard or even possibly the graphics card(s). In this case, it is safe to say that the PSU, the usual culprit, and the graphics card have been eliminated as suspects. Capacitors do not need to be leaking to be faulty and there is always the possibility that another component on the mobo, like a mosfet could be failing, but they usually don't fail unless the capacitor which supplies it fails first. In short, it's time to once again RMA the mobo and move to Gigabyte which equips their boards with solid caps.
Like you, I have been partial to Asus for many years but have completely switched my shop over to Gigabyte. Asus has decided to sell off all their hardware assets to become just a "brand" like Antec. They still have a good name and have decided to cash in on that. My guess is that they will milk the company dry.

Thanks for the speedy responses guys!

To address both posts:

I stripped the system down to just a motherboard, CPU and 1 stick of RAM, on-board VGA only, not even a case or front panel header. Occasionally it would boot up fine, but sometimes it wouldn't. I initially thought it was various hardware components as I introduced them, but I quickly realized the failures were random.

I thought it was a PSU issue to begin with, which is why I replaced my Antec 430W with a brand new Enermax NAXN 550W, this seemed to fix the problem at first, but the no-post issue returned after first reboot. I also tested on a third power supply and experienced the same results. I have tried booting without the graphics card, just using onboard VGA, and still have issues.

I'm just waiting for this RMA to process. I will definitely look into Gigabyte. I miss the days when ASUS was worth the extra dime. I still have 12 year old Asus boards that are running fine, this is an indictment of the unfortunate drop in ASUS' build quality in the last few years.

Second the motion on Gigabyte boards. I haven't used an Asus board since 2004. The one i have now is listed on my signature, and even though its not the highest end one, it is one of the best according to them at the capacitor lifespan. Guaranteed also. I only paid like $79.00 for it and it is one of the best boards i ever owned. Flawless as can be. Backup bios,50,000 hr caps, etc.. I run all latest high end games without a hickup. LOL

I remember reading something about 50,000 hour solid caps on the box for my ASUS... HAH! The only way I can use my computer right now is if I turn it on first thing in the morning and DO NOT reboot or enter standby. It seems to need at least 12 hours of rest between shutdowns. However, my PS2 keyboard fails within 1 hour of using the computer. Considering I bought this board in a bundle with the Phenom 9600 for less than $100, I guess I can't complain. It has given me 2.5 years of use...

Well, this issue can be put to rest. It was a motherboard problem. I received a brand new replacement motherboard from ASUS on Monday, installed everything, updated the BIOS and it works great. Its nice to see ASUS had some concept of their error in customer service, the board was shipped using same day delivery, and was actually new this time, not an RMA refurb. Thanks to all who chimed in, I'm a little less baffled now :)

Cheers gents.

I have the exact same problem with my M4N78 Pro. Yesterday it went completely dead. Tried the same stuff you did, even a new PSU. Glad to hear it was under warranty now I have to figure out if mine is . . .