Comment 15 for bug 391461

it is the kernel.. it's the method of PAT forcing back to MTRRs, so this may be per CPU basis and not related to GPU's.

There has been a work around for those who have installed using the binary (this work around is NOT for third party inclusion)
diff -ru usr/src/nv/nv.c usr/src/nv.572433/nv.c
--- usr/src/nv/nv.c 2009-05-27 03:20:53.000000000 -0700
+++ usr/src/nv.572433/nv.c 2009-07-05 11:31:27.635210006 -0700
@@ -888,6 +888,7 @@
     unsigned int pat1, pat2, i;
     U008 PAT_WC_index;

+#if 0 /* disabled */
     if (!test_bit(X86_FEATURE_PAT,
             (volatile unsigned long *)&boot_cpu_data.x86_capability))
     {
@@ -895,6 +896,7 @@
             "NVRM: CPU does not support the PAT, falling back to MTRRs.\n");
         return NV_PAT_MODE_DISABLED;
     }
+#endif

     NV_READ_PAT_ENTRIES(pat1, pat2);
     PAT_WC_index = 0xf;

You can get all the info from nvidia's site:
http://www.nvnews.net/vbulletin/showthread.php?t=133112&page=1

or more directly this post:
http://www.nvnews.net/vbulletin/showpost.php?p=2041755&postcount=29