I switched from a h67 motherboard to a z68 based one (asrock z68 pro3). Problems were apparent immediately, with lockups happening after a few seconds/minutes (usually sooner rather than later but sometimes it went for longer). Sometimes everything froze, but mostly a black screen with some vertical flicking pixels. machine has to be powered off to bring it back.

I got some slightly better stability by overvolting the gpu slightly from within the bios, but it didn't solve the issue. As everything was fine when booting to windows, i had a nose at the code related to power saving, as I suspected it was related to this. and indeed by disabling the power saving code "gen6_enable_rps" my system is stable with no crashes.

Not ruling out a bug with the mb/bios/chipset implementation of course, as everything was fine when the cpu was on my h67 based board. Please do give me some guidance on how to help further with this. for now, I'm happy to have a usable system. Ill provide lspci -v and dmidecode logs, let me know if you need more.

my quick hack to disable power saving:

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index aa43e7b..06627ec 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7787,8 +7787,8 @@ void intel_modeset_init(struct drm_device *dev)
                intel_init_emon(dev);
        }
 
-       if (IS_GEN6(dev))
-               gen6_enable_rps(dev_priv);
+       //if (IS_GEN6(dev))
+               //gen6_enable_rps(dev_priv);
 
        INIT_WORK(&dev_priv->idle_work, intel_idle_update);
        setup_timer(&dev_priv->idle_timer, intel_gpu_idle_timer,
@@ -7829,8 +7829,8 @@ void intel_modeset_cleanup(struct drm_device *dev)
 
        if (IS_IRONLAKE_M(dev))
                ironlake_disable_drps(dev);
-       if (IS_GEN6(dev))
-               gen6_disable_rps(dev);
+       //if (IS_GEN6(dev))
+       //      gen6_disable_rps(dev);
 
        if (IS_IRONLAKE_M(dev))
                ironlake_disable_rc6(dev);

pretty serious bug anyway as makes the system pretty much unusable without it. I hope a real fix can be found.