TX750M random shut downs with Xfire

[Sigurd]

Hi,

For 2 weeks now I have been getting random shutdowns. This happens only when I have both my HD6950s installed. When I take one of them out, the problem does not occur. It doesn't matter which one; I tried both the cards separately to rule out a faulty graphicscard. I also replaced the crossfirebridge to check if that is broken, but no.

I figured it would be a power issue, but the shutdowns do not only happen at load, but at idle as well. So even when it just sits there running Windows, but nothing else, and me not even in the same room, it still does random shutdowns.

Before this problem started, the system had been running fine for 5 months.
I did not change any hardware, it just started happening for no apparent reason.

Sometimes my monitor flickers a bit before it happens, but most of the time it just goes black and loses all power.

Please help me figure out what the problem is.
Thank you

[Sigurd]

Still looking for help with this ^

[RAM GUY]

I think you may need a bigger PSU these Video cards are not on our PSU configurator but if I do the same configuration with two 5900 series GPU's the minimum is 950 Watt. But for one of these cards a 750 Watt should be okay.

[Sigurd]

This setup came recommended by Tweakers.net
The HD6950's are the reason I upgraded my old 620W to this 750W one.
Many people use this PSU with these cards.
And if the PSU can't handle crossfire, why does it have 4 PCI-E connectors?
The whole system was running fine for 5 months.

I think it is just faulty. It just crashed twice with only 1 vgacard installed. I checked the BIOS and found this:

CPU Voltage [1.104V]
3.3V Voltage [2.704V]
5V Voltage [6.128V]
12V Voltage [14.329V]

These values seem way off to me.
Reason enough to RMA?

[peanutz94]

You can not trust the BIOS readings or any other software for that fact when it comes to voltages.. Those readings have to be wrong. Your PC would not boot at 14v if those voltages were correct. If it did it wouldn't last long.
The best way is to test them with a multimeter.to be sure. There have been plenty of people come through here with abnormal PSU voltages in the BIOS and were completely normal when tested with an accurate meter. More often than not the sensors that read the voltage are not accurate.

This issue could go either way. It may be a PSU or your MB.

I would do a little more digging before you RMA'd anything.

And if the PSU can't handle crossfire, why does it have 4 PCI-E connectors?
The whole system was running fine for 5 months.

There are many different crossfire set-ups and not one of them will require the same amount of voltage or in this case wattage. If your 2 card draw more than what the PSU can handle then you run into issues. This is where you need to pay attention to power demands of your cards

If you run your system through the Corsair PSU configurator they list no less than a 950 watt PSU min and a 1200 w as the best optiion. I'll agrree that is not really needed for what you have. And AMD recommends a 500w PSU just for one card. Sorry i think you are just taxing the PSU and it cant handle two of those cards.*shrugs*

[Sigurd]

I already RMAed my MB and CPU. They were tested and they told me they couldn't find any hardware issues.

Those voltage readings were just after the computer crashed and would not reboot until I took the power off completely for a minute or so.

If the voltage readings in the BIOS are unreliable, then why are they there? That's just pointless.

500W for one card means 500W+250W = 750W for 2 cards.
The 750W rating on this PSU is not peak power, its advertized as constant power. Suggesting that I buy a 950W or even 1200W one is too easy and silly. Simply "throwing more Watts at it" is not a solution.

Most importantly:
As explained in my previous post, it crashes with 1 VGAcard too now. 750W for a single VGA is more than enough, don't you agree?

[RAM GUY]

We can try and RMA the PSU that is not a problem, but I think you may end up in the same position with this configuration from what I can find you should be using a larger PSU with two of these cards.
Please use the link on the left to request an RMA and we can replace it.

[peanutz94]

If the voltage readings in the BIOS are unreliable, then why are they there? That's just pointless.

They are supposed to be somewhat accurate. But it's been proven over and over that they just cant be trusted. Any

I have seen them off buy a lot more than what your are being reported. At 14v you would be frying connectors!