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#1 2025-02-27 13:32:31

256
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Registered: 2023-12-17
Posts: 78
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[SOLVED] Overscan on multi-monitor setup

I recently added a 1080p screen to my PC over a HDMI port, in addition to a 1920x1200 screen over DVI that I was already using before. The 1920x1200 screen still works fine, but the 1080p one is overscanned (zoomed in so you can't see the edges, and what you can see is blurry due to resizing). This monitor has worked fine in the past, including on GNU/Linux installs on this same machine if memory serves.

Output of xrandr --prop (EDIDs snipped out):

Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192
VGA-1 disconnected primary (normal left inverted right x axis y axis)
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	load detection: 1 
		range: (0, 1)
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 47 
		supported: 47
	non-desktop: 0 
		range: (0, 1)
HDMI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 480mm x 270mm
	audio: auto 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	dither: off 
		supported: off, on
	underscan vborder: 27 
		range: (0, 128)
	underscan hborder: 48 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	coherent: 1 
		range: (0, 1)
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 49 
		supported: 49
	non-desktop: 0 
		range: (0, 1)
   1920x1080     60.00*+  59.96    50.00    59.94    59.93  
   1920x1200     59.95  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     65.00    60.00  
   1680x1050     59.95    59.88  
   1400x1050     74.76    59.98    59.95  
   1600x900      59.94    59.95    59.82  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      75.00  
   1280x720      60.00    59.99    59.86    60.00    50.00    59.94    59.74  
   1440x576      50.00  
   1024x768      75.05    60.04    75.03    70.07    60.00  
   960x720       75.00    60.00  
   1440x480      60.00    59.94  
   928x696       75.00    60.05  
   896x672       75.05    60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   832x624       74.55  
   960x540       59.96    59.99    59.63    59.82  
   800x600       75.00    70.00    65.00    60.00    72.19    75.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   720x576       50.00  
   720x576i      50.00  
   700x525       74.76    59.98  
   800x450       59.95    59.82  
   720x480       60.00    59.94  
   720x480i      60.00    59.94  
   640x512       75.02    60.02  
   700x450       59.96    59.88  
   640x480       60.00    75.00    72.81    75.00    66.67    60.00    59.94  
   720x405       59.51    58.99  
   720x400       70.08  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   576x432       75.00  
   640x360       59.86    59.83    59.84    59.32  
   512x384       75.03    70.07    60.00  
   512x288       60.00    59.92  
   416x312       74.66  
   480x270       59.63    59.82  
   400x300       72.19    75.12    60.32    56.34  
   432x243       59.92    59.57  
   320x240       72.81    75.00    60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DVI-I-1 connected 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
	load detection: 1 
		range: (0, 1)
	audio: auto 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	dither: off 
		supported: off, on
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	coherent: 1 
		range: (0, 1)
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 51 
		supported: 51
	non-desktop: 0 
		range: (0, 1)
   1920x1200     59.95*+
   1920x1080     59.96    60.00    59.93  
   1600x1200     65.00    60.00  
   1680x1050     59.95    59.88  
   1400x1050     59.98  
   1600x900      59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    70.07    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       70.00    65.00    60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   720x400       70.08  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   640x360       59.86    59.83    59.84    59.32  
   512x384       70.07    60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  

Using "xrandr --output HDMI-1 --set underscan on" and doing the necessary hborder/vborder setting technically fixed the overscan, but everything was still blurry, like when you resize an image and then resize it back to its original size. Twiddling with the monitor's own settings menu with the buttons on the side didn't reveal anything useful. Some of the threads I found about this had to with TVs being used as monitors, but that's not an issue here.

Here's my GPU (from sudo lspci -vv):

02:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV620 LE [Radeon HD 3450] (prog-if 00 [VGA controller])
        Subsystem: Dell Device 9018
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 27
        NUMA node: 0
        Region 0: Memory at d0000000 (64-bit, prefetchable) [size=256M]
        Region 2: Memory at fdff0000 (64-bit, non-prefetchable) [size=64K]
        Region 4: I/O ports at e000 [size=256]
        Expansion ROM at 000c0000 [disabled] [size=128K]
        Capabilities: [50] Power Management version 3
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Express (v2) Legacy Endpoint, IntMsgNum 0
                DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <4us, L1 unlimited
                        ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset- TEE-IO-
                DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
                        RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
                        MaxPayload 128 bytes, MaxReadReq 128 bytes
                DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
                LnkCap: Port #0, Speed 2.5GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
                        ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp-
                LnkCtl: ASPM Disabled; RCB 64 bytes, LnkDisable- CommClk+
                        ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
                LnkSta: Speed 2.5GT/s, Width x16
                        TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
                DevCap2: Completion Timeout: Not Supported, TimeoutDis- NROPrPrP- LTR-
                         10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-
                         EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
                         FRS-
                         AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-
                         AtomicOpsCtl: ReqEn-
                         IDOReq- IDOCompl- LTR- EmergencyPowerReductionReq-
                         10BitTagReq- OBFF Disabled, EETLPPrefixBlk-
                LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
                         Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
                         Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
                LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
                         EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
                         Retimer- 2Retimers- CrosslinkRes: unsupported
        Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
                Address: 00000000fee01000  Data: 0026
        Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
        Kernel driver in use: radeon
        Kernel modules: radeon, amdgpu

The last thing I can think of is xrandr's --transform option, but wouldn't that have the same problem with blurring as underscan?

I'm using i3, if it matters.

Last edited by 256 (2025-02-27 16:32:53)


"Don't comment bad code - rewrite it." - The Elements of Programming Style (1978), Brian W. Kernighan & P. J. Plauger, p. 144.

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#2 2025-02-27 16:13:19

seth
Member
From: Won't reply 2 private help req
Registered: 2012-09-03
Posts: 75,086

Re: [SOLVED] Overscan on multi-monitor setup

technically fixed the overscan, but everything was still blurry

Yes, you have to fix that in the monitor (tv?) by disabling the overscan there.
Compensating by underscanning the source is a kludge to at least get you the full image on display, but it will never be a good solution.

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#3 2025-02-27 16:32:29

256
Member
Registered: 2023-12-17
Posts: 78
Website

Re: [SOLVED] Overscan on multi-monitor setup

seth wrote:

Yes, you have to fix that in the monitor (tv?) by disabling the overscan there.
Compensating by underscanning the source is a kludge to at least get you the full image on display, but it will never be a good solution.

Oh! I gave up on the monitor's settings because the most promising looking options were greyed out. The relevant setting was actually under "input select", which I disregarded earlier as being unimportant. I set it to "HDMI PC" from "HDMI AV" (what does AV stand for?). Now it works.


"Don't comment bad code - rewrite it." - The Elements of Programming Style (1978), Brian W. Kernighan & P. J. Plauger, p. 144.

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