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GPU not working and low voltage readings

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a b V Motherboard
April 23, 2012 9:32:56 AM

Hi all,

I recently purchased the M5A78L-M/UBS3 to replace my old M2NPV-VM. I replaced the board (and obviously the RAM) only; all other components were carried over from the old board.

My problem is that the board does not boot when the GPU is plugged in. I get output from the card for a few seconds, and then the display dies, even when I'm in the BIOS screen. Rebooting the PC after that does not bring the display back. The onboard HD3000 appears to work fine, along with all other connected components.

The only apparent clue I can find is that the voltage readings in Windows appear far too low. +12V is only about 7.9V, and +5V reads as 3.9V. Readings were taken using CPUID HWMonitor and Pirifom Speccy; both give the same values. In BIOS though, the voltage readings appear correct. I'm not sure which reading to trust.

If the problem is power related, I may know why it's happening. The motherboard documentation recommends a power supply with a 24pin main connector. My Antec Basiq BPU500 has a 20+4, not the 24pin. It does however have 18A on the 12V rail, which will work according to the specification (15A is recommended). This may still not be good enough though.

At this point I am at a loss as to what the problem is. Any advice on how I can narrow it down?

Thanks in advance.
April 23, 2012 10:17:54 AM

First here's explanation what's the difference between 20+4 and 24 pin PSU. 24 pin PSU you can connect only to MoBo that requires 24pin PSU, 20+4 means you can slide off last 4 pins and connect it to 20 pin MoBo. Otherwise in theory there is no difference between 20+4 and 24 pin PSU, all differences are related more to make and model, than to number and configuration of pins.
My guess is that either MoBo is problem. If you still have old MoBo and RAM try to assemble PC, if it boots up properly it's MoBo, RAM never creates such problems with voltage. If problem persist it's pointing toward faulty PSU more than toward GPU, but you can be certain of that only if you can borrow somewhere PSU that is proven as in working order and trying it on your PC. Of course if problem persists with working PSU it's GPU.
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a b V Motherboard
April 23, 2012 10:24:06 AM

I should point out that both the PSU and GPU were working 100% fine on the same day just prior to me replacing the mobo. So I would not think that they are to blame.
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a b V Motherboard
April 23, 2012 10:30:52 AM

Your voltages are fine. The BIOS or OEM utilities are the best source for voltage information since it knows the nuances of the hardware sensors. On my system, 3rd party tools tell me my +12V rail is at 10.38V but the MSI control center accurately tell that it's at 11.79V.
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a b V Motherboard
April 23, 2012 10:33:16 AM

That's good to know; I will install the Asus PC monitor tools that came with the mobo to see what they report.
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April 23, 2012 10:33:22 AM

Sorry, forgot to say that amps are maximum specs and components can draw less amps if they need, so more is always better concerning possible future upgrades with components that require higher amperage. An forgot to ask you did you use Molex to PEG power converter or dedicated 6 pin connector for GPU? If you have used converter switch to dedicated, if not that's just another thing pointing toward faulty PSU.
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a b V Motherboard
April 23, 2012 10:35:48 AM

hetneo said:
Sorry, forgot to say that amps are maximum specs and components can draw less amps if they need, so more is always better concerning possible future upgrades with components that require higher amperage. An forgot to ask you did you use Molex to PEG power converter or dedicated 6 pin connector for GPU? If you have used converter switch to dedicated, if not that's just another thing pointing toward faulty PSU.


The PSU has a dedicated 6pin which is what I am using currently.
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a c 156 V Motherboard
April 23, 2012 10:45:53 AM

If your 12 volt reading actually was 7.9 volts, your system would not boot. You would never get the "PowerGood" signal from the power supply that the CPU/motherboard needs to boot.

So, you upgraded the motherboard and RAM. The rest of your components came from an existing, working system. And the RAM works with the embedded graphics.

Two possibilities: the video card died in the transplant process or you have a problem with the motherboard.

Test the video card in another system.
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a b V Motherboard
April 23, 2012 10:52:36 AM

jsc said:
If your 12 volt reading actually was 7.9 volts, your system would not boot. You would never get the "PowerGood" signal from the power supply that the CPU/motherboard needs to boot.


Good point; I was wondering about that.
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a b V Motherboard
April 23, 2012 4:37:31 PM

OK, some more info: Windows fails to boot with the GPU installed, as I mentioned. When I reset, the screen doesn't come back because it then automatically switches to the on-board graphics again. The error message reads: The boot selection failed because a required device is inaccessible. Code 0xc0000225. It asks if I want to boot normally or do a repair installation. Normal boot then gets me back to Windows.

Any ideas?
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a b V Motherboard
April 23, 2012 5:07:14 PM

The first thing I would do:
1) remove GPU
2) boot to a memtest 86 Boot CD and run Memtest, at least for 4 hours to verify No errors.
3) If no errors, boot to windows (GPU still disconnected) run prime95, Only need to run for about 15 Min to check +12 V rail. Run for 4 hours min to verify cpu and memory stability. Monitor the +12 V rail for 15 Min. A) use Asus utility to monitor, or you can try the "new" release Of HWMonitor - the Old x.18 did NOT work for a lot of MBs. or B) the best method is to use a digital Voltmeter. They ARE: Cheap (About $15 @ walmart, Easy to use (Just google How to use a voltmeter) and, lastly they are very handy around the House and car. For a Voltmeter, just insert the Black meter lead into one of the center pins (black wire) of a Molex power connector and the Red meter lead into the Molex connector with the orqnge wire - at one end (Note molex read wire is the +5 V).
+12 V must NOT drop below 11.4 V which is the spec (I use min +12 V = no lower than 11.6V.

If everything is good, That is +12 V is good and No memory errors runing Prime 95 then the problem most likely is the GPU, also coud be a problem with the MB pci-e connector

Added:
Have you verified that the MB has the Lates Vios firmware??
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a b V Motherboard
April 23, 2012 7:37:25 PM

Thanks, I have a multimeter lying around so I will check the voltage readings. I already updated HWMonitor to 1.19; no change.

Memory seems an unlikely culprit since the PC boots fine with the onboard GPU. I see there are several new BIOS versions for my board, so will try one of those as well.
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a b V Motherboard
April 23, 2012 8:19:39 PM

Quick voltage check done while running 3DMark2006. I used an unconnected Molex connector and tested DC volts from ground to the yellow wire while the system was under load. 12V readings are steady between 12.2 and 12.15. Unless I did this wrong, the power supply appears to be working fine.
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a b V Motherboard
April 24, 2012 2:19:52 AM

Have to agree PSU seems fine. Would not have read thoughes voltages if done incorrect - Only two outputs + 5 and +12 on Molex.

Checking memory was more a Verify that it is OK, befor going in to windows an loading the System with Prime 95, 3Dmark2006 should be about as good, I normally use furmark or Prime 95 to load the +12V.

So that now kind of puts the onous on either the GPU or the MB.
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a b V Motherboard
April 24, 2012 7:38:39 AM

I tend to agree. Next step will be to test the GPU elsewhere, then possibly do a BIOS upgrade on the mobo. I see there are a number of recent updates available beyond the version it's currently running.
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a b V Motherboard
April 25, 2012 8:07:26 AM

OK, so the BIOS update did nothing. By plugging in cables to both the 6850 and the onboard GPU simultaneously, I have confirmed that the PC starts up and detects the display, then it works for about 20-30 seconds whether I try to boot Windows or just stay in BIOS. Then the display loses signal, and it defaults to onboard GPU as soon as I restart.

I am quickly running out of ideas here...
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a b V Motherboard
April 26, 2012 7:07:35 AM

I tried two other GPU's; my semi-broken 9800GTX and an old 6600 PCIe I borrowed from a friend. Neither card is detected at all on startup.

By using the quick boot option (ie, most POST tests are skipped), I actually managed to get as far as my Windows desktop with the 6850 before it stopped working again. There is definitly a finite wait time between bootup and the crash occuring. It doesn;t appear to be triggered by any particular event during startup.

I'm really starting to think I have a dud PCIe slot. Any more comments?
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a b V Motherboard
April 29, 2012 4:29:33 PM

Old board back and everything working again. Closer inspection of the PCIe slot on the new board revealed a bent pin lying across the bottom. That appears to be the cause of the problem and explains why everything else on the board worked perfectly. I will return it for a replacement.

Thanks for all the help and suggestions.
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a b V Motherboard
April 29, 2012 4:30:51 PM

Best answer selected by Herr_Koos.
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a c 328 V Motherboard
April 29, 2012 5:09:38 PM

This topic has been closed by Nikorr
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