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Single OK - SLI Strange

Last response: in Graphics & Displays
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January 13, 2012 9:26:57 AM

Hi there everyone,

i've got a strange problem since yesterday.
I changed my DDR3 1366 RAM (12GB) with DDR3 1600 RAM (24GB).

My system overview is:
i7 930
DDR3 1600
Asus P6 Pro
2x GTX480 with SLI
1000W be quit Power Supply

After i changed the RAM, the system worked fine, until i recognized, that i unplugged one of the external power cables of the second 480gtx. So i turned off the system, replugged the cable and started it again.
It was plugged in before, so it got unplugged while changing the RAM.

No i have strange behavior:

As soon as i plug in both gtx480 with power supply, the moment Windows 7 is starting and the login screen appears, the CPU load is about 80% to 100%.... the system is working slow...you still can do everything...but very slow. I can setup SLI and i can test it.

If i unplug one gtx480 and it doesn't matter which one (tested both and started Windows), the system works fine and runs like hell. I have a good knowledge about computer hardware, but now i am confused.

Gonna change the RAM back tonight (at work right now), but with only one gtx480 everything is fine, so i guess if the RAM could be a problem, i should have some problems with just one gtx480 too.

Things i already did:

Checking for any kind of virus or system infection.
Adjusting CPU and DRAM Voltage to might get things stable (after no effect, back to normal).
Reinstall video drivers.
Pray.

Things i gonna do soon:

Changing RAM back to old one.


And ideas?

Greetz
Andrew

More about : single sli strange

January 13, 2012 10:03:38 AM

Yes ram ,do u have high knowledge in hw so why u r buy 2 ram with different mhz both are work in1333Mhz fine , if u oc into 1600Mhz ram the other wont possible so system behave like this
January 13, 2012 10:07:47 AM

crosswire or sli needs more mhz from ur ram to upload files at startup so u r system unstable
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January 13, 2012 10:08:24 AM

hitechgowthaman said:
Yes ram ,do u have high knowledge in hw so why u r buy 2 ram with different mhz both are work in1333Mhz fine , if u oc into 1600Mhz ram the other wont possible so system behave like this

What if the OP replaced the 1333mhz RAM with the 1600mhz RAM? That's the way I read it and if I'm correct then you need to work on your reading comprehension (and while you're at it, give the grammar a brush up).
January 13, 2012 11:21:46 AM

I had 6 DIMMs 1333 with 2Gb/DIMM , now i upgraded to 6 DIMMs 1600 with 4Gb/DIMM.
I've made some adjustment concerning mainboard settings (Timings, Speed) so it matches with the new memory. (6-6-6-24 to 9-9-9-24)

The system is not unstable, it is just slow because cpu load is nonstop between 80% - 100% (no tasks running). And it is not only at the startup, its till shutdown.

The only thing i would think of concerns the short time only the 8 pin external power cable was connected to the second 480gtx (missing the 6pin one). Could this damage a card?
January 13, 2012 12:33:02 PM

Have you determined if a particular 480 is giving you the trouble? YOu says its fine with 1 plugged in, but what if you swap which card is plugged in?
Seems to me the ram is not the issue, but what happened to one of the cards in the process of swapping the ram.
January 13, 2012 12:40:15 PM

I tested both cards as Single (remaining in the same pci-e slots).
Unplugged the 8 Pin and 6 Pin power cable from one and system works fine.
Doing this for the second card, the same.

When i was swapping the ram, i accidently unplugged the 6 pin power cable from the second 480gtx.
The system was running with only the 8 pin power cable connected to the second card till i recognized, i could not activate SLI and i check again. So i reconnected the 6 pin cable.
!