Can't get 2560x1440 on GT520
I'm wondering if anyone can give me any advice or point me in the right direction.
My problem is that my new GT520 can't achieve the max resolution of my screen but my old GeForce 8400GS can.
Some base facts to start:
* Driver: 275.09.07 (Linux-x86_64 on Ubuntu 10.10 but also tried 11.04)
* New card (not working fully): GT520 (ASUS GT520 silent), 1GB
* Old card (works perfectly): GeForce 8400GS, 512MB
* Monitor: Dell U2711, panel res 2560x1440
* Cable: Dual link DVI
* Monitor appears to give correct EDID information
I've tried many settings combinations in my xorg.conf but no matter what, the GT520 will not produce above 1920x1200. Now, I'm pretty sure it's not an EDID thing as that information does seem to be picked up correctly by the driver. However, this mode is rejected on the GT520 card with the message "2560x1440 exceeds hardware capabilties".
(II) NVIDIA(0): Validating Mode "2560x1440":
(II) NVIDIA(0): 2560 x 1440 @ 60 Hz
(II) NVIDIA(0): Mode Source: EDID
(II) NVIDIA(0): Pixel Clock : 241.50 MHz
(II) NVIDIA(0): HRes, HSyncStart : 2560, 2608
(II) NVIDIA(0): HSyncEnd, HTotal : 2640, 2720
(II) NVIDIA(0): VRes, VSyncStart : 1440, 1443
(II) NVIDIA(0): VSyncEnd, VTotal : 1448, 1481
(II) NVIDIA(0): H/V Polarity : +/-
(II) NVIDIA(GPU-0): BestFit Scaled and BestFit AspectScaled are identical;
(II) NVIDIA(GPU-0): collapsing BestFit AspectScaled.
(II) NVIDIA(GPU-0): BestFit Centered and BestFit Scaled are identical;
(II) NVIDIA(GPU-0): collapsing BestFit Scaled.
(II) NVIDIA(GPU-0): Native Scaled and Native AspectScaled are identical;
(II) NVIDIA(GPU-0): collapsing Native AspectScaled.
(II) NVIDIA(GPU-0): Native Centered and Native Scaled are identical;
(II) NVIDIA(GPU-0): collapsing Native Scaled.
(II) NVIDIA(GPU-0): BestFit and Native are identical; collapsing Native.
(WW) NVIDIA(GPU-0): BestFit Centered ViewPort 2560x1440 exceeds hardware
(WW) NVIDIA(GPU-0): capabilities.
(WW) NVIDIA(0): Mode is rejected: Unable to construct hardware-specific
(WW) NVIDIA(0): mode timings.
The card is specced for up to 2560x1600, so it should be able to do it. I am currently guessing that it's something to do with the Adaptive clocking of the card and that at initialisation time the clock is under the level needed to make a 2560x1440@60Hz screen (241.50 MHz pixel clock) so that mode is getting rejected.
I've tried playing around with the Coolbits and PowerMizer settings in the xorg.conf as well as adding options nvidia NVreg_RegistryDwords="PerfLevelSrc=0x2222" into a modprobe.d configuration file as my gut feeling is that I need to make sure the GT520 is running at full speed during initialisation. However, no amount of tweaking has worked so far. Am I looking in the wrong direction? Might there be a bug with the 275.09.07 driver in that it isn't maxing the graphics card's clocks during initialisation?
Attached are two log files, one from the GT520 card and one from the 8400GS with the very same xorg.conf file. The xorg.conf file is very vanilla, with just Option "ModeDebug" "TRUE" in the monitor section and with Option "Coolbits" "1" in the device section (not that that seems to make a difference) - so nothing interesting there. I've attached the xorg.conf file just for completeness.
Any ideas or help would be much appreciated!