Can't startx in 24b color depth mode

[T <mlist4suntong@yahoo.com>]

Hi, 

I can't startx in 24b color depth mode, I'm wondering why.

I tried to startx in 24b color depth mode with

startx -- -depth 16 :1

I can see the intial X backgroud (with the cursor), but then it went back
to console text mode. To verify, I tried

startx -- :1

and it worked. 

Comparing the 2 logs, there is nothing significant except this:

@@ -509,3 +509,3 @@
 (--) RADEON(0): VideoRAM: 131072 kByte (64 bit DDR SDRAM)
-(II) RADEON(0): PCI card detected
+(II) RADEON(0): AGP card detected
 (II) Loading sub module "ddc"

The full diff output is included at the end.

Here is my Screen Section, if that might be a hint:

Section "Screen"
	Identifier	"Default Screen"
	Device		"ATI Technologies, Inc. RV280 [Radeon 9200 SE]"
	Monitor		"SyncMaster"
	DefaultDepth	16
	SubSection "Display"
		Depth		1
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth		4
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth		8
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth		15
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth		16
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth		24
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
EndSection


$ diff -wu1 /var/log/XFree86.1.log.old /var/log/XFree86.1.log
--- /var/log/XFree86.1.log.old  2005-11-29 18:10:29.000000000 -0500
+++ /var/log/XFree86.1.log      2005-11-29 18:10:55.000000000 -0500
@@ -24,3 +24,3 @@
          (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
-(==) Log file: "/var/log/XFree86.1.log", Time: Tue Nov 29 18:10:20 2005
+(==) Log file: "/var/log/XFree86.1.log", Time: Tue Nov 29 18:10:40 2005
 (==) Using config file: "/etc/X11/XF86Config-4"
@@ -492,7 +492,7 @@
 (II) RADEON(0): PCI bus 1 card 0 func 0
-(++) RADEON(0): Depth 24, (--) framebuffer bpp 32
-(II) RADEON(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps)
+(**) RADEON(0): Depth 16, (--) framebuffer bpp 16
+(II) RADEON(0): Pixel depth = 16 bits stored in 2 bytes (16 bpp pixmaps)
 (==) RADEON(0): Default visual is TrueColor
-(==) RADEON(0): RGB weight 888
-(II) RADEON(0): Using 8 bits per RGB (8 bit DAC)
+(==) RADEON(0): RGB weight 565
+(II) RADEON(0): Using 6 bits per RGB (8 bit DAC)
 (II) Loading sub module "int10"
@@ -509,3 +509,3 @@
 (--) RADEON(0): VideoRAM: 131072 kByte (64 bit DDR SDRAM)
-(II) RADEON(0): PCI card detected
+(II) RADEON(0): AGP card detected
 (II) Loading sub module "ddc"
@@ -704,2 +704,3 @@
        ABI class: XFree86 Video Driver, version 0.6
+(II) RADEON(0): AGP Fast Write disabled by default
 (II) RADEON(0): Depth moves disabled by default
@@ -714,3 +715,2 @@
        of this adapter, please see http://gatos.sf.net.
-(--) Depth 24 pixmap format is 32 bpp
 (II) do I need RAC?  No, I don't.
@@ -862,3 +862,3 @@
 (II) RADEON(0): Using hardware cursor (scanline 770)
-(II) RADEON(0): Largest offscreen area available: 1024 x 7417
+(II) RADEON(0): Largest offscreen area available: 1024 x 7413
 (**) Option "dpms"

Please help. Thanks a lot

T