Overclocking screen refresh rate question

I have overclocked the chi mei n173hge-l11 FHD screen on the Clevo in my sig to 90Hz . I checked for frame skipping, color profile corruption ... etc. and everything seems to be ok.

My question would be in the bandwidth limitations of the dual LVDS connection between the screen and motherboard and the 40 pin cable, can they take the new almost double bandwidth of the overclock (5.60 Gbps for 90Hz vs 3.73 Gbps for 60Hz) without overheating and dying prematurely or causing fire or so ?

@t456 any insight on the topic?

 

Unlike eDP LVDS was never officially rated for such high speeds, but the rare desktop variant could do over 5 Gbps with a few tweaks and mandating cables with twisted pairs. Almost every laptop cable is like that, so the cable shouldn't be an issue. The real limit is with the screen itself. Some have managed to kill them by oc'ing, probably by overloading one of the controller chips. Very rare though and 90Hz is fairly conservative.

Just don't push it to just below artifacting; find the limit by adding 5Hz each time and drop a safe 10Hz or so below that. That there's no visible artifacting does not mean the panel is happy and a borked lcd isn't like an oc-induced cpu hiccup, after all.

 

The screen I have does 100 Hz without artifacting and more interestingly without even skipping frames so I can safely say it can do at least 100 Hz in a stable manner. I didn't try higher because I don't want to push my luck so I settled with 90 Hz as it is even 10 Hz lower than the 100 Hz.

So you think if this is the case 90 Hz may be on the "ok" side, I won't say safe side because overclocking and safe don't mix?

 

Yes, seems perfectly 'safe'. Also have to set it off against the potential cost; the L11 isn't a very expensive screen, so if a possible $45 setback doesn't cause too many worries then the smooth gameplay might be well worth it. Could also drop in a cheaper, compatible model for as little as $30.

Run all my panels non-stock and never had an issue. Yet n=1 isn't a good indicator for anything, so off-setting the pro's vs the con's is always a good idea.

 

As long as it is the screen that will die I am perfectly fine That's why I asked if the motherboard connection and wire are ok. Gratitude Sir, you have been as helpful as always.

 

Interesting, I have not seen dead screens from overclocking but the normal rules do apply about being careful and leaving margin I guess.

 

With how low QC is in electronics now. I wouldn't be surprised if anything fails. Even when operated within standard specs.

 

Yes but we are talking fairly low power here fortunately most power in a panel is the back light.

 

Yes, that's why I'd suspect the transmitter chip, the cmos-converter or, only remotely, the small dc-dc buck converter used to drive the lcd part of the input.

Both LVDS and eDP use an LVDS transmitter, which might seem a bit weird for both situations. Thing is that the actual display itself is still driven by LVDS (the technology, not the protocol), even a modern 'eDP'-type. The proper name for LVDS-the-protocol is really FPD-Link, but that became synonymous with LVDS-the-wire-technology. A LAN cable uses LVDS too, for instance, but we wouldn't think to call CAT5 'LVDS'.

Anyway, for an LVDS display the LVDS transmitter merely smooths the signal to the tighter margin required by the lcd (RSDS). But with an eDP panel it has do a more complex conversion and uses about twice the energy. For both types that isn't the end-point either; last step is conversion from LVDS/RSDS to LVCMOS powering the actual crystals.

The transmitters and cmos converter have specified limitations in Gbits/s and operating temperature. Overclocking obviously wasn't factored in when choosing these chips, so it'll depend on the quality of the components as to how far it'll go. As always with oc'ing; could heatsink them or even add a tiny fan.

Still have a Sharp 1920x1200 CCFL that's about 13 years old by now. It was one of the first if not the first 1080p(+) laptop panel, so think they overdesigned it just to be on the safe side; it runs at 185Hz before it starts artifacting. Too bad it's not 16:9, otherwise I might transplant it to a newer system; CCFL is far easier on the eyes than WLED, so it'd make a great office worker.

 

By the heavens! 13 years old and 185 Hz on a laptop screen. I always thought these crazy refresh rates were reserved in the past to CRT monitors. You have a treasure

 

Yes, monitor can borked up. One ChiMei worked at 100Hz, 2nd one got vertical line after being at 96.

Good they are cheap now.