diff --git a/drivers/video/matrox/g450_pll.c b/drivers/video/matrox/g450_pll.c
index 440272ad10e725a206e58491e0e6b1bf96a1d5a8..7c76e079ca7d378495f4d4b27e583531e0da172a 100644
--- a/drivers/video/matrox/g450_pll.c
+++ b/drivers/video/matrox/g450_pll.c
@@ -331,7 +331,15 @@ static int __g450_setclk(WPMINFO unsigned int fout, unsigned int pll,
 					tmp |= M1064_XPIXCLKCTRL_PLL_UP;
 				}
 				matroxfb_DAC_out(PMINFO M1064_XPIXCLKCTRL, tmp);
+#ifdef __powerpc__
+				/* This is necessary to avoid jitter on PowerPC
+				 * (OpenFirmware) systems, but apparently
+				 * introduces jitter, at least on a x86-64
+				 * using DVI.
+				 * A simple workaround is disable for non-PPC.
+				 */
 				matroxfb_DAC_out(PMINFO M1064_XDVICLKCTRL, 0);
+#endif /* __powerpc__ */
 				matroxfb_DAC_out(PMINFO M1064_XPWRCTRL, xpwrctrl);
 
 				matroxfb_DAC_unlock_irqrestore(flags);