Hardware Canucks - Help Needed...GTX 560 on SLI Slower than Non-SLI

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Help Needed...GTX 560 on SLI Slower than Non-SLI

Hello guys:

It is my first post on this forum, so I hope I can find some answers to the questions that I have from all of you out there.

This is my case scenario. I recently built a PC from new and used components with hopes of improving my gaming experience.
My hardware includes:

Motherboard: Gigabyte 990FXA-UD3
VGA: 2x GTX-560 (non-Ti) 1GB of VRAM/card.
CPU: Athlon 64 X4 640 @ 3.6 Ghz
8 GB DDR3 @1333 Mhz
PSU: 750 Watt Cooler Master 80 Plus Bronze.
Hard Drive: 250 GB Samsung 5400 rpm
Screen Resolution: 1920x1080
Win 7 64-bit

Games that I've played so far with this PC are:
Skyrim
Battlefield 3

Whenever I play with one card I get steady frame rates between:
Skyrim (Ultra): 30-50 FPS
Battlefield 3 (High): 30-50 FPS

The issue is that when I enable SLI I get lower performance than with a single card, and even worse, when playing Battlefield 3 at the beginning seems fine with 60-65 FPS but after two or three minutes it becomes unplayable.

My question is:
What do you suggest to improve my system? (With the current hardware)

Also, I ran this hardware with an AMD FX-6100 @ 4.2 Ghz and the performance was even lower that those numbers up there.

Thank you.

2 things that I can think of off the top of my head:

1) Are you using recent nvidia drivers?
2) How are your cpu and gpu temperatures? Perhaps there is throttling occuring if you are running hot.
3) maybe the hard drive is causing problems? Kind of a longshot but it may be too slow.

What about running a benchmark such as 3dmark and measuring with sli and without. See if you can reproduce it in a synthetic test.

Quote:

Originally Posted by dandelioneater (Post 620119)

1) I am using the 295.73 because when I had the latest one installed youtube would freeze while on fullscreen. I read that other people were having the same issue as me and that the only solution they found was to roll back to their previous driver.
2) CPU temp with prime 95 ~ 63 C
3) I wasn't too worried about HDD becuase I know it only affects loading times and loading times IMO have been decently good.