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Added 2nd 6950, computer won't start

Last response: in Graphics & Displays
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April 13, 2012 1:31:01 AM

Hello,

I just added a second 6950 to my setup, and now I have two in crossfire. Only problem is, my computer now won't boot. It turns on, all the fans and lights turn on, and it even shows the initial screen listing all the components, but then the screen turns black and it stays that way. What's wrong and how do I solve it? Any advice would be appreciated.

EDIT: I can actually even access the BIOS still. Not sure what this means, but interesting.

Specs:
i5-2500K OC'd to 4.4
8GB Corsair Vengeance 1333 RAM
Gigabyte GA-Z68X-UD3H-B3 mobo
Corsair TX650 V2 PSU

-Charlie
a b U Graphics card
April 13, 2012 11:34:10 AM

well that PSU is not SLI certified for a 560ti SLI (equivalent to 6950 Crossfire) so probably that is the problem, test each card alone and see if both are working, if yes, you need another PSU for that job.

here is the Nvidia List:
http://www.geforce.com/Active/en_US/en_US/pdf/PSU.pdf

Check those that can handle the 560ti SLI and you can go with those for your 6950 Crossfire
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a c 291 U Graphics card
April 13, 2012 11:39:00 AM

I'm pretty sure that power supply is powerful enough. hd 6950 eats less energy than GTX 560 Ti, and I saw people run GTX 560 Ti SLI with 620w power supply. One way to check if it's power issue, set CPU multiplier to default. If it still doesn't work, you can try x16 multiplier (for 1.6 GHz). It will be slow, but at least you know it's not your hardware.

Another theory is that one of cards are bad or the motherboard PCIe slot is bad.
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a b U Graphics card
April 13, 2012 11:45:01 AM

650w seems a bit light, could be the problem
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a b U Graphics card
April 13, 2012 11:54:54 AM

it can work at very stock systems, but he overclock the CPU that already pulls much more energy from the PSU, it will probably work with default clocks.
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April 13, 2012 12:12:11 PM

Alright well I'll try setting everything back to stock clocks and report back. Thanks for the help everyone.
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a b U Graphics card
April 13, 2012 1:26:49 PM

Power should be adequate, but you will not have much in reserve.

A pair of 6950's pull about 27 - 28 amps peak 3D load, but only 4 or 5 amps in a 2D desktop load or while booting[/]. An OC'd CPU will pull about 10 amps, leaving plenty of power for the rest of the system.

The voltage increase needed for a major Intel CPU overclock will increase CPU power consumption by about 20% - 25%. That sounds like a lot, but it actually amounts to no more than about 30 watts.

Suggestions:
Go back to stock speeds and check.
Make sure you have the latest video drivers.

Test each video card separately to make sure they both work.

Next step is to borrow a good 750 - 800 watt PSU. You have a better than average PSU, but there could be something wrong with it.

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April 13, 2012 3:27:22 PM

Okay, well I just put my CPU back to stock clocks and then tested each card individually and with the one I already had everything works perfectly, but with my new one the computer seems to start...and then commences an endless boot loop. Does this mean the card is dead? Is there any way to fix it? Or do I have to get another one?

Thanks everyone.
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a b U Graphics card
April 13, 2012 3:36:07 PM

could also be the pci-e slot on your mobo
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April 13, 2012 3:36:54 PM

neon neophyte said:
could also be the pci-e slot on your mobo

But the old card works in the same slot that the new one doesn't.
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a b U Graphics card
April 13, 2012 3:37:23 PM

ah, then id rma that card
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April 13, 2012 3:49:22 PM

neon neophyte said:
ah, then id rma that card

Yeah, thanks, that's what I'm going to do.
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April 13, 2012 3:54:30 PM

id try booting into safe mode / reinstalling windows before rma'ing
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April 13, 2012 4:07:48 PM

Try the new card in another system
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April 13, 2012 4:09:20 PM

osamabinrobot said:
id try booting into safe mode / reinstalling windows before rma'ing

How can I boot into safe mode when my system is boot looping?
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a b U Graphics card
April 13, 2012 4:11:53 PM

MANOFKRYPTONAK said:
It is recommended you have at minimum a 700 W.
Link: http://forum-en.msi.com/faq/article/power-requirements-...
Egg also recommends at minimum 700W

I thought it was more like 800W SLI ready in real world applications, hopes that solves it!


actually it will really depende What 700W psu, his 650W corsair gives more than 700W and can handle SLI/Crossfire, but it is really at the maximum limit for 6950.

Some 700W psu can't go over 450W with efficiency that is the difference between good brands and generic brands.

Best is always check if your PSU is really certified for the CrossFire/SLI.


Quote:
Okay, well I just put my CPU back to stock clocks and then tested each card individually and with the one I already had everything works perfectly, but with my new one the computer seems to start...and then commences an endless boot loop. Does this mean the card is dead? Is there any way to fix it? Or do I have to get another one?

Thanks everyone.


yes probably that card is defective, but make sure it was defective from the beggining, its hard but there is a remote possibility that your psu did that to the GPU when you have tested the Crossfire with overclocked CPU.

First thing RMA IT, when the new one gets there, test it alone firrst, (without cpu overclocks) than you connect Both (without cpu overclock) if they are working normally at stress tests, than you can try the overclock.

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April 13, 2012 4:16:47 PM

^ I agree with him.
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a b U Graphics card
April 13, 2012 10:18:44 PM

Before you do anything, take out the "new" card and put the "older" card in the PCIe slot you had the "new" card in and try to boot. Could be the slot and not the card... you could also just switch the cards and test.

To force safe mode tap F8 during the post screen.
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April 13, 2012 11:54:56 PM

RussK1 said:
Before you do anything, take out the "new" card and put the "older" card in the PCIe slot you had the "new" card in and try to boot. Could be the slot and not the card... you could also just switch the cards and test.

To force safe mode tap F8 during the post screen.

Already tried both cards in the same slot, old one worked, new one didn't.
And just tried safe mode with the new card, no dice.
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a b U Graphics card
April 13, 2012 11:59:31 PM

cskoler said:
Already tried both cards in the same slot, old one worked, new one didn't.
And just tried safe mode with the new card, no dice.


Yeah, unfortunate but it happens. RMA time... :( 

Good luck!
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April 14, 2012 12:00:52 AM

ricardois said:
actually it will really depende What 700W psu, his 650W corsair gives more than 700W and can handle SLI/Crossfire, but it is really at the maximum limit for 6950.

Some 700W psu can't go over 450W with efficiency that is the difference between good brands and generic brands.

Best is always check if your PSU is really certified for the CrossFire/SLI.


Quote:
Okay, well I just put my CPU back to stock clocks and then tested each card individually and with the one I already had everything works perfectly, but with my new one the computer seems to start...and then commences an endless boot loop. Does this mean the card is dead? Is there any way to fix it? Or do I have to get another one?

Thanks everyone.


yes probably that card is defective, but make sure it was defective from the beggining, its hard but there is a remote possibility that your psu did that to the GPU when you have tested the Crossfire with overclocked CPU.

First thing RMA IT, when the new one gets there, test it alone firrst, (without cpu overclocks) than you connect Both (without cpu overclock) if they are working normally at stress tests, than you can try the overclock.

Well I actually bought it used off eBay (something I would not normally do) because 6950 2GB's are no longer in stock for reasonable prices from normal retailers. So I just sent the eBayer a message saying the card was defective and am going to ship it back tomorrow and will receive a replacement.
Also, my PSU is Crossfire certified and I was told by several people here at TH that that PSU would be sufficient to power 6950's in Crossfire.
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a b U Graphics card
April 14, 2012 12:22:23 AM

cskoler said:
Well I actually bought it used off eBay (something I would not normally do) because 6950 2GB's are no longer in stock for reasonable prices from normal retailers. So I just sent the eBayer a message saying the card was defective and am going to ship it back tomorrow and will receive a replacement.
Also, my PSU is Crossfire certified and I was told by several people here at TH that that PSU would be sufficient to power 6950's in Crossfire.


What did you pay for it? I have a xfx 6950 2gb I'm selling.
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April 14, 2012 12:40:35 AM

RussK1 said:
What did you pay for it? I have a xfx 6950 2gb I'm selling.

$200 for lightly used
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!