ASUS Motherboard fails to post/no video

Oct 28, 2018
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After bench testing in the case, I removed the motherboard, PSU and HD and installed them into an industrial case to power a CNC mill. After the move I no longer have video out of the built in VGA.


Step three: History
When was the last time the computer worked right? Two weeks ago when I tested it in the house with the same monitor and VGA cable.

Was there something that happened right before things got bad? The only change was removing the mother board and PSU from the case and moving it into a NEMA type enclosure. I removed the stands and used them to mount the board in the new enclosure
Did you install some hardware? I did install a MESA 5i25 and 7i77 control board into the PCi slots. These have been removed for testing. The last time the computer worked both of these were installed.
Did you install some software? I did the last time it was operational. I installed Linux CNC and ran a Max Jitter test to verify functionality

Step four: The Full Story:

I am building a CNC control system for my Bridgeport mill. I acquired several old desktops and pieced together a working system. The only parts I really need were the mother board and cpu assembly, a hard drive and PSU. I scavenged all of these and tested the set up in the original case on my kitchen table before moving them to the shop where they will be installed in a well cooled NEMA type industrial enclosure. I mounted the Mobo using the standoffs from the case and some expoxy to hold the studs to the box. The screws were installed and left just short of snug. The PSU initially didn't turn on when testing in the new enclosure. I removed it and bread board tested it by shorting green to black and everything tested fine. Reinstalled and it was operational. I then tried booting the computer. The LED power light comes on(both on the mobo and the external I took from the computer case. The hard drive spins up, the CPU fan comes on. But the monitor remains black with the power saving message. I get no beeps from the CPU speaker.

Step five: The specs
CPU AMD Phenom II HD700EOCK3DGI
Motherboard ASUS m2n68-am
RAM (2) CRUCIAL CT25664AA800.K16F 2 GB 240-PIN DDR2 DIMM UNBUFF
CPU cooler ThermalTake
Video Card Built in Shader Model 3.0 DirectX 9
Power Supply 400w ATX
Hard drive(s) 1 500 GB DESKSTAR by Hitachi, SATA
Operating System Linux CNC Weezy
Case Breadboard currently, installed in a large NEMA style enclosure with 4 fans and filtered inlet
Other Items: Logitech K400 Wireless Keyboard via USB dongle, Dell wired key board.

Step six:

1.Did you carefully read the motherboard owners manual? Yes link here

https://dlcdnets.asus.com/pub/ASUS/mb/socketAM2/M2N68-AM_Plus/E4428_M2N68-AM_PLUS-manual.zip

2. Did you plug in the 4/8-pin CPU power connector located near the CPU socket? Yes and back probed for appropriate voltages

3.Did you install the standoffs under the motherboard? Did you place them so they all align with the screw holes in the motherboard, with no extra standoffs touching the board in the wrong place? Yes, but I only installed 4. The are very lightly screwed to the Mobo and epoxied to the enclosure. There is no errant epoxy or other items touching the board.I used a multi-meter and verified all 6 mounting holes are connected to ground.

4.Did you verify that the video card is fully seated? (may require more force than a new builder expects.) I don't see a video card. I'm assuming the MoBo has built in graphics based on the specs in the users manual. Integrated Programmable Shader Model 3.0 DirectX 9 Graphics Processor.

5.Did you attach ALL the required power connector(s) to the video card? (some need two, some need none, many need one.) It is best to use cables connected directly to the PSU. Only use adapters if absolutely necessary. Yes, I am connecting a 24 pin to the Mobo as well as a 4 pin 12ATX and the hard drive connector. I have tried to boot with the hard drive unpluged with no effect.


6.Have you tried booting with just one stick of RAM installed? Yes. I have tried with no ram(Got the BEEEEEEP BEEP BEEP). Shut down and installed one stick, no beeps. Removed and tried the other stick, no beeps. No effect on issue.

7.Did you verify that all memory modules are fully inserted?Yes, cleaned slots with compressed air and made sure they were fully seated.

8.Did you verify in the owners manual that you're using the correct RAM slots? Yes they are installed correctly and were not moved since the computer last functioned correctly.

9.Did you remove the plastic guard over the CPU socket?Not applicable

10.Did you install the CPU correctly? CPU was not removed before the issue started. I have since removed it, clean the socket, checked for bent,broken, damaged pins. None found. Reassembled and tested, no effect.

11.Are there any bent pins on the motherboard/CPU? No

12. If using an after market CPU cooler, did you get any thermal paste on the motherboard, CPU socket, or CPU pins? Did you use the smallest amount you could?No errant paste. I have inspected the mobo with a magnifying glass. It is super clean.

13.Is the CPU fan plugged in? Yes and operating. There is a separate plug for a chassis fan that is unplugged, but it was unplugged the last time the computer was bread boaded.

14. If using a stock cooler, was the thermal material on the base of the cooler free of foreign material, and did you remove any protective covering? If the stock cooler has push-pins, did you ensure that all four pins snapped securely into place? N/A

15. Are any loose screws laying on the motherboard, or jammed against it? Are there any wires run directly under the motherboard? You should not run wires under the motherboard since the soldered wires on the underside of the motherboard can cut into the insulation on the wires and cause a short. Some cases have space to run wires on the back side of the motherboard tray.
no

16.Did you ensure you discharged all static electricity before touching any of your components? Yes, working on a concrete floor

17.Did you install the system speaker (if provided) so you can check beep-codes in the manual? Speaker installed and proven operational during ram testing

18.Did you read the instructions in the manual on how to properly connect the front panel plugs? Yes, only using power switch and power LED. Both working as advertised

19.Did you turn on the power supply switch located on the back of the PSU? Yes, PSU is on and back probed for appropriate voltages under load. No issue found. Have tested with two other known good PSU with no effect

20.Is your CPU supported by the BIOS revision installed on your motherboard? Unsure as I get zero graphics, but this bios/software and hardware was all working properly before.

21.Have you tried resetting the CMOS?
Yes multiple times. I removed the 2032 Battery the first time. Then removed battery and changed the jumper, then removed battery and currently have the jumper connected overnight. The battery read 2.5volts which could be an issue. I will get a new one in the morning.

22. If you have integrated video and a video card, try the integrated video port. Resetting the bios, can make it default back to the on board video. If you are trying to use HDMI outputs, try using DVI or VGA instead. Sometimes the HDMI ports won't work until the correct drivers are installed.
I only have a single VGA output from the mother board.

23. Make certain all cables and components including RAM and expansion cards are tight within their sockets. Done multiple times


"Pull everything except the CPU and HSF. Boot. You should hear a series of long single beeps indicating memory problems. Silence here indicates, in probable order, a bad PSU, motherboard, or CPU - or a bad installation where something is shorting and shutting down the PSU.
tried this with multiple known good PSU's and no effect. No beeps. Hard Drive and HSF both run as normal. Power LED on steady, no video.

To eliminate the possibility of a bad installation where something is shorting and shutting down the PSU, you will need to pull the motherboard out of the case and reassemble the components on an insulated surface. Done no effect


If you get the one long and two or three short beeps, test the rest of the RAM. If good, install the video card and any needed power cables and plug in the monitor. If the video card is good, the system should successfully POST (one short beep, usually) and you will see the boot screen and messages. Tried no ram, got the beeps. Installed each stick and tried to boot, no beeps, no video.

Note - an inadequate PSU will cause a failure here or any step later. Have tried three known good PSU's and back probed for voltage. No change.


"The best way to check the PSU is to swap it with a known good PSU of similar capacity. Brand new, out of the box, untested does not count as a known good PSU. PSU's, like all components, can be DOA. I have three, 400w, 300w, 230w All have been bench tested and back probed under load and pass. No effect on issue

Next best thing is to get (or borrow) a digital multi-meter and check the PSU.
I have one and have checked all power and grounds and no faults found.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot. verified with multi-meter

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
have done this and bench tested all. No issues found

I have used two different know good monitors and two different know good vga cables. VGA cables have been tested and found fault free from the monitor end to the back side on the VGA connector on the Mobo. I am certain the issue is on/in the Mobo
 

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