Is the "FPS fix", in fact, "detrimental"?

[DaveNagy]

Hi all,

I'll be getting an Evo this month, so I've been researching ROMs. I came across this passage in the "AC-ROM" sticky, and wasn't sure what to make of it:

Q) Will this ROM fix the FPS issue?
A) No, the FPS cap is still in place. You may see people suggesting you download a custom kernel to remove the FPS cap, WE HIGHLY SUGGEST YOU DO NOT DO THIS! While the kernel may or may not work, the way the FPS "fix" is being implemented is detrimental to the life of your EVO and a waste of battery. The cap has not been removed in these kernels, rather, your LCD screen is being told to refresh twice as fast meaning more battery used and shorter life on your LCD screen (by 200%). We will implement a fix when a proper fix is identified that will not cause damage to your EVO. We care about your EVO as much as you do. Thanks for understanding.​

That was the first I had heard of such a concern, and my subsequent Googling hasn't turned up any further discussion along these lines.

So, what's the scoop? Are the AC-ROM guys describing the issue correctly? Is this a legitimate concern?

 

[Jerzyiroc]

Depends on who you talk to. Those against it will say what you quoted in your post. However, those that are for it will say that the Evo has the same screen as the HD2 and the HD2 refreshes its screen twice as much as the Evo normally. So since they share the same screen then there should be no negative affects from increasing the refresh rate on the Evo since the HD2 does it anyway...

 

[jrun]

If thats true.. my screen will definitely be living a shorter life.. hah.. Hopefully that 200% reduction in life is still greater than 2 years.. cause thats when the contracts up

 

[PedroTheGoat]

I somehow think the "damaging to screen" stuff is poppycock.

 

[DaveNagy]

Heck, my brain hurts when I try to decide what "200% reduction in life" even means.

Well, okay. In the absence of any compelling evidence, I think I'll assume that the "fix" is largely harmless. It seems like the following would need to be true for there to be any risk:

• HTC must have coded things so the display refreshes at 60 Hz (utterly typical), but the framerate is locked in such a way that each frame is forced to last for two refreshes. (This could easily be the case if v-sync is enabled, and the phone can't quite ever manage to render at 60 FPS. eg. 59 FPS would be truncated to 30 FPS.)
• The fix works by upping the display refresh rate to 120Hz (unlikely, and maybe impossible), while also turning off v-sync. (If v-sync was left on, a theoretical 59 FPS would display at ~40FPS, max. 3 refreshes per frame.)

Hmmm. Okay, the only part of that that seems unlikely is the 120Hz display part. Are these screens actually capable of such a rate? That would be highly unusual on a desktop LCD, but maybe the pocket sized ones are different.

Or..... What happens if you drive a 60Hz display with a 120Hz signal? Maybe it works fine. If that's possible, then a fix like the one I described (okay, made up) could possibly work pretty well. It certainly wouldn't harm the display, but it would make the output side of the GPU work harder than it needed to. That would (slightly) increase power consumption.

But, I'm pulling all of this out of my ***. Does anyone know of a thread where this was discussed?