diff --git a/headers/private/graphics/nvidia/DriverInterface.h b/headers/private/graphics/nvidia/DriverInterface.h
index 2afe854c34..d97279ffc2 100644
--- a/headers/private/graphics/nvidia/DriverInterface.h
+++ b/headers/private/graphics/nvidia/DriverInterface.h
@@ -5,7 +5,7 @@
 	Other authors:
 	Mark Watson;
 	Apsed;
-	Rudolf Cornelissen 10/2002-4/2003.
+	Rudolf Cornelissen 10/2002-12/2003.
 */
 
 #ifndef DRIVERINTERFACE_H
@@ -200,7 +200,9 @@ typedef struct {
 		CH7006,
 		CH7007,
 		SAA7102,
+		SAA7104,
 		SAA7108,
+		SAA7114,
 		BT868,
 		BT869,
 		CX25870,
@@ -249,13 +251,16 @@ typedef struct {
 		uint32 memory_size;			/* memory (Mb) */
 	} ps;
 
-  /*mirror of the ROM (copied in driver, because may not be mapped permanently - only over fb)*/
+	/* mirror of the ROM (copied in driver, because may not be mapped permanently - only over fb) */
 	uint8 rom_mirror[32768];
 
-  /*CRTC delay -> used in timing for MAVEN, depending on which CRTC is driving it*/
+	/* CRTC delay -> used in timing for MAVEN, depending on which CRTC is driving it */
 	uint8 crtc_delay;
 
-  /* apsed: some configuration settings from ~/config/settings/kernel/drivers/nv.settings if exists */
+	/* NV31 (FX5600) tweak to get pixelPLL going (unknown register) */
+	uint16 pixpll_vco_div2;
+
+	/* apsed: some configuration settings from ~/config/settings/kernel/drivers/nv.settings if exists */
 	settings settings;
 
 	struct
diff --git a/src/add-ons/accelerants/nvidia/engine/nv_dac.c b/src/add-ons/accelerants/nvidia/engine/nv_dac.c
index c66f1a32d5..be4cef401d 100644
--- a/src/add-ons/accelerants/nvidia/engine/nv_dac.c
+++ b/src/add-ons/accelerants/nvidia/engine/nv_dac.c
@@ -1,6 +1,6 @@
 /* program the DAC */
 /* Author:
-   Rudolf Cornelissen 7/2003
+   Rudolf Cornelissen 12/2003
 */
 
 #define MODULE_BIT 0x00010000
@@ -234,6 +234,9 @@ static status_t nv4_nv10_nv20_dac_pix_pll_find(
 		/* check if this is within range of the VCO specs */
 		if ((f_vco >= si->ps.min_pixel_vco) && (f_vco <= si->ps.max_pixel_vco))
 		{
+			/* NV31 (FX5600) tweak (missing register for 2nd VCO postscaler) */
+			f_vco /= si->pixpll_vco_div2;
+
 			/* iterate trough all valid reference-frequency postscaler settings */
 			for (m = 7; m <= 14; m++)
 			{
@@ -246,7 +249,9 @@ static status_t nv4_nv10_nv20_dac_pix_pll_find(
 				if ((n < 1) || (n > 255))	continue;
 
 				/* find error in frequency this setting gives */
-				error = fabs(req_pclk - (((si->ps.f_ref / m) * n) / p));
+				/* si->pixpll_vco_div2 below is NV31 (FX5600) tweak (missing register) */
+				error =
+					fabs((req_pclk / si->pixpll_vco_div2) - (((si->ps.f_ref / m) * n) / p));
 
 				/* note the setting if best yet */
 				if (error < error_best)
@@ -267,6 +272,9 @@ static status_t nv4_nv10_nv20_dac_pix_pll_find(
 
 	/* log the VCO frequency found */
 	f_vco = ((si->ps.f_ref / m) * n);
+	/* NV31 (FX5600) tweak (missing register for 2nd VCO postscaler) */
+	f_vco *= si->pixpll_vco_div2;
+
 	LOG(2,("DAC: pix VCO frequency found %fMhz\n", f_vco));
 
 	/* return the results */
diff --git a/src/add-ons/accelerants/nvidia/engine/nv_general.c b/src/add-ons/accelerants/nvidia/engine/nv_general.c
index 39a9c8fe55..1d161033c7 100644
--- a/src/add-ons/accelerants/nvidia/engine/nv_general.c
+++ b/src/add-ons/accelerants/nvidia/engine/nv_general.c
@@ -81,7 +81,7 @@ status_t nv_general_powerup()
 {
 	status_t status;
 
-	LOG(1,("POWERUP: nVidia (open)BeOS Accelerant 0.07 running.\n"));
+	LOG(1,("POWERUP: nVidia (open)BeOS Accelerant 0.08-1 running.\n"));
 
 	/* preset no laptop */
 	si->ps.laptop = false;
@@ -819,6 +819,31 @@ status_t nv_general_bios_to_powergraphics()
 		NV_REG32(NV32_2FUNCSEL) &= ~0x00001000;
 	}
 
+	//fixme: FX5600 cards have a second postdivider for the pixel PLL VCO.
+	//find it and program it, instead of relying on the cards BIOS...
+	//BIOS tested: FX5600 BIOS V4.31.20.38.00
+	/* non-NV31 cards have no second postdivider */
+	si->pixpll_vco_div2 = 1;
+	if (si->ps.card_type == NV31)
+	{
+		/* only reading b0-7, as the rest seems to be write-only */
+		uint16 v_display = CRTCR(VDISPE) + 1;
+		if ((!(CRTCR(REPAINT1) & 0x01)) &&
+			((v_display == (600 & 0xff)) || (v_display == (1200 & 0xff))))
+		{
+			/* if a VESA mode was already set, and the mode was 800x600 or 1600x1200
+			 * the BIOS programs the second VCO postdivider to 5 */
+			si->pixpll_vco_div2 = 5;
+			LOG(2, ("INIT: assuming NV31 pixPLL second VCO postdivider is set to 5!\n"));
+		}
+		else
+		{
+			/* else the BIOS programs the second VCO postdivider to 4 */
+			si->pixpll_vco_div2 = 4;
+			LOG(2, ("INIT: assuming NV31 pixPLL second VCO postdiviver is set to 4!\n"));
+		}
+	}
+
 	/* enable 'enhanced mode', enable Vsync & Hsync,
 	 * set DAC palette to 8-bit width, disable large screen */
 	CRTCW(REPAINT1, 0x04);