Tom's Hardware > Forum > Motherboards & Memory > General Motherboard > Asus P5N72-T Won't reboot without cmos clear

Asus P5N72-T Won't reboot without cmos clear

Forum Motherboards & Memory : General Motherboard - Asus P5N72-T Won't reboot without cmos clear

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justtroitin   08-26-2008 at 05:09:41 PM

I'm building a new PC from scratch. I work in the IT industry, so I'm not a complete novice at such things. My specs are as follows:

Motherboard: Asus P5n72-T Premium
Processor: Intel Core2 Quad Q9450
Memory: G.Skill F2-8500CL5D DDR2-1066 (I have a total of 8GB, however am currently only running one 2GB Dimm for troubleshooting purposes)
Vid Card: PNY NVidia GeForce 9800 GX2 1024MB

I have a single SATA drive installed and a SATA DVD-RW. Everything else I have disconnected from the board for troubleshooting.

The problem that I'm having is the PC will not boot unless I clear the CMOS via the jumper on the motherboard. This includes entering the BIOS and making any changes. Once I save changes and reboot I get no display, no post beep, nothing...

I have Windows Vista Home Premium 64bit installed by just clearing the CMOS everytime I reboot. It appears to run fine while in Windows, however I did experience two lock ups at misc times.

In addition, this is not my first motherboard. The first one did the same thing and I had it replaced for the same model via Newegg. The 2nd board is doing the same exact thing.

On the old board I did update the BIOS to the newest version, also replaced the BIOS battery. This made no change. I have not yet done these things with the new board.

Any ideas? Thanks!

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evongugg   08-26-2008 at 05:30:35 PM
- 0 +

Welcome to the forums!

Is the memory at the right voltage?
Try lowering the speed of the memory to 666 MHZ.
Try alternating the memory stick.
Try a different brand of memory if you can.

------------------------------ Google is your friend and Bob's your uncle
 Reply to evongugg
evongugg   08-26-2008 at 05:39:34 PM
- 0 +

The right voltage for your memory should be 2.0-2.1v.

------------------------------ Google is your friend and Bob's your uncle
 Reply to evongugg
justtroitin   08-26-2008 at 06:02:45 PM
- 0 +

I have tried manually setting the voltage to both 2.0 and 2.1 with the same results. As soon as I exit and save changes, no post, no display, until I clear the cmos once again (which of course kills any settings I have made).

With this board I didn't have any other brands of memory to test, but I did with the previous and had the same results with settings at Auto. I will have a few different types of memory to test with tonight when I can continue troubleshooting.

Just an FYI, with the settings at Auto the voltage monitor in the BIOS states my memory is running at 1.9~1.92v.

Thanks for the help!

Edit: almost forgot, no I have not tried setting the memory to 666 Mhz, but will do so tonight.


Message edited by justtroitin on 08-26-2008 at 06:04:28 PM
Reply to justtroitin
justtroitin   08-27-2008 at 12:10:41 AM
- 0 +

I had a little time to troubleshoot a bit more, so here is a bit more info.

I disconnected all of my SATA devices for troubleshooting purposes.

I tried a stick of Samsung memory I borrowed from work and had the same issue.

I performed the disable splash screen only, same results.

I also tried dumbing the memory down to both 666 and 800, still no go.

I did find that I could enter the bios and as long as I didn't save, it would reboot and post properly, though I would get the same CMOS checksum error from the original CMOS clear.

Something else I found that after a failed post, if I moved the stick of RAM to a different slot, it would sometimes boot and give me the previous post failed error, please enter setup and reset defaults. Of course if I do so, I'm back at square one.

Reply to justtroitin
justtroitin   08-27-2008 at 03:58:12 AM
- 0 +

Well, I think I've had it with this MB. I know Asus has a great reputation as a MB manufacturer, so I would still like to stick with them. I'm also not currently running SLI, but would like the option in the future.

That being the case, can anyone recommend a board that would be a good fit for my existing hardware?

I'm currently leaning toward the ASUS Striker II Formula LGA 775 NVIDIA nForce 780i SLI ATX Intel Motherboard.

G.Skill has it on their list of tested MB's, so that's a plus.

Thoughts?

Reply to justtroitin
evongugg   08-27-2008 at 01:33:46 PM
- 0 +

You could get a 750i chipset motherboard also, which is a little cheaper.

------------------------------ Google is your friend and Bob's your uncle
 Reply to evongugg
Axe69   04-06-2009 at 01:44:18 PM
- 0 +

I'll reply to this chain although it's quite old.

I have exact the same problem with my Asrock 4CoreDual-SATA2 r2.0 mobo with Pentium Dual-Core e5200 -processor. The problem appeared when I updated the processor; everything is okay with the old one (Pentium 4 641).

Any ideas? Should I abandon this mobo or is there something that I can try?

Reply to Axe69
Anno   09-13-2009 at 05:59:39 AM
- 0 +

I am seeing this problem with an Asus P5Q SE Plus. I can boot into Windows and run for days after clearing CMOS. But after saving any BIOS settings, the screen stays blank and I am not even getting the first beep from the VGA POST, although fans and disks are spinning.

This thread is helpful. I am suspecting my power supply, which is 380W and Asus recommends 400W. The power supply as root cause is consistent with justtroitin's replacement board having the same symptoms, and Axel69's processor upgrade making the difference.

Message quoted 1 times
Reply to Anno
vulmer   09-13-2009 at 07:15:58 AM
- 0 +

Anno wrote :

I am seeing this problem with an Asus P5Q SE Plus. I can boot into Windows and run for days after clearing CMOS. But after saving any BIOS settings, the screen stays blank and I am not even getting the first beep from the VGA POST, although fans and disks are spinning.

This thread is helpful. I am suspecting my power supply, which is 380W and Asus recommends 400W. The power supply as root cause is consistent with justtroitin's replacement board having the same symptoms, and Axel69's processor upgrade making the difference.



Had the same thing happen today with one of my computers. It is also a P5Q SE Plus. After clearing CMOS everything seems fine but I have had to do it twice so far. I don't think it is your PSU as I am using a 750wat corsair.

Reply to vulmer
Anno   09-15-2009 at 02:56:36 AM
- 0 +

Thank you for shooting down that theory before I ordered a new PSU. I will try a replacement MB before my 30 days are up.

Reply to Anno
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