Underclock and Overclock the SH4

[poursoul]

Is it a command line switch. Like, can I make a shortcut for it and add an argument?

Because I'm not seeing an option for it anywhere in the program itself.

In the help file it says:

The "CPU 100" displays the current speed of the SH4, the main CPU in the dreamcast console. Since Chankast v0.2, you have the possibility to overclock and underclock the CPU to affect the emulation speed during gameplay with the following keys:

+ Overclock the SH4

- Undercolock the SH4

The clock speed ranges from 50% up to any value you can imagine. If you have a slow PC, you might gain some speed if you underclock the CPU slightly. Faster PCs can get more FPS than the actual dreamcast by increasing the clock rate - useful by getting past slowdowns or other stuff.

Would those be the switches?

[s250]

Press "+" or "-" on number pad.

[PhysicienXS]

The switches are "+" to overclock and "-" to underclock.

[nsignific]

Doesn't actually DO anything though, does it. I got best results setting it to 50 in Soul Calibur, and the higher it went the slower the game worked.

[Bobbi]

Originally Posted by nsignific

Doesn't actually DO anything though, does it. I got best results setting it to 50 in Soul Calibur, and the higher it went the slower the game worked.

Quote from the official manual:

The clock speed ranges from 50% up to any value you can imagine. If you have a slow PC, you might gain some speed if you underclock the CPU slightly.

So overclocking the SH4 *over* 100 actually slows down stuff.

[jareg]

In the manual it says that people with more powerful Pc will have a speed increase when they increase the Cpu over 100 but i have heard that all the users will get a speed increase if they decrease the Cpu under 100
Thats weird

Maybe someone with a really powerful Pc should try this Like Razor Blade

[nsignific]

Underclocking to50% also seems to halve the FPS dreamcast pushes to 50%, which actually means frameskipping, at least that's the only way I can exlplain it, since you're not actually underclocking anything.

[dc_cd]

it's just say if you increase the SH4 clock,you can get more frame which make the game see more smooth,the problem is you must have powerful pc to show these frame in one second.I am sorry for my poor english and hope you can understand what i say.

[D.Strange]

I have powerfull CPU, so that is results - in SoulCalibur and DoA2 same thing - if i underclocking SH4 to 80, fps is increasing and i can play DoA2 at 32FPS instead of 24 - but if i trying overclock SH4 then FPS is decreasing... There is no speed increasing by overclocking SH4...

[Rayden-X]

You are misunderstanding. By underclocking the CPU there are less cpu cycles per vertical refresh. Thus the game can appear to run faster if it isn't really pushing the CPU as all those extra cycles wasting time don't happen. But, if a game was really pushing the CPU, underclocking would more than likely have little to no effect in increasing speed.

If you overclock the CPU, if the CPU normally couldn't handle things fast enough, it may be able to then. If you try Metal Slug for NeoGeo, you'll notice at the default setting there is significant slowdown. Overclock the CPU (which means it takes MORE power to emulate fast) and the game no longer has those slowdowns.

The thing is, with Dreamcast, have you ever really noticed a game with slowdown? I haven't. However for those with lesser CPUs underclocking can be very nice.

For my situation I don't believe the CPU is holding me back, I think it's my video card.

[n_w95482]

Originally Posted by Rayden-X

The thing is, with Dreamcast, have you ever really noticed a game with slowdown? I haven't.

Sega Rally 2 has an almost constant case of slowdown. Sometimes it jumps up to 60 FPS temporarily (during some parts of time trials and at the end of races), otherwise it's around 20-30 (estimate).

[Aion-san]

Well, at 100% soul calibur is very slow everywhere at any moments.

When i push it to more than 150%, i can play normally without a moment lag on about 80% of the game.

Drop the directx renderer and wait for an opengl one (OpenGl can't render some effects but can emulated them far more quickly than directx. It also has a better system that makes polygons render in a pyramidal form, wich increases the speed)

[Rayden-X]

I was refering to have you ever see a Dreamcast game running on the actual Dreamcast hardware suffering from slowdown. Few to none do.

[n_w95482]

Originally Posted by Rayden-X

I was refering to have you ever see a Dreamcast game running on the actual Dreamcast hardware suffering from slowdown. Few to none do.

If you are talking about my post, I was referring to the actual hardware. I've just started playing Sonic Adventure (on the actual console) and I noticed that has some slowdown but it's pretty rare.

[ector]

Originally Posted by Aion-san

Drop the directx renderer and wait for an opengl one (OpenGl can't render some effects but can emulated them far more quickly than directx. It also has a better system that makes polygons render in a pyramidal form, wich increases the speed)

PYRAMIDAL form? I have TONS of experience with Direct3D and a bit with OpenGL too, and I have never heard of "pyramidal" polygon rendering. That's just bull****. If you are talking about mipmapping (where people sometimes talk about a "pyramid" of ever smaller versions of a texture, but that's not very common terminology), Direct3D has full support for that and Chanka uses it.

Regarding your claim that OpenGL is faster than Direct3D, it is true that OpenGL is somewhat faster at rendering many small batches of polygons, which is how the dreamcast works. However, Chanka collect polygons into bigger batches before submitting then to Direct3D, so that speed advantage is almost negated. I would expect to see a SMALL speed increase from switching it to OpenGL though.

Besides, in another thread you stated that Dolphin uses OpenGL. I wrote the Dolphin GFX plugin. It uses Direct3D, nothing else. I use Direct3D because I know it best. If somehow the Dolphin CPU core would ever become fast enough to run games properly, I might rewrite the plugin to OpenGL to gain an FPS or two, but right now it's not worth it.

So, please quit talking about stuff you have no clue whatsoever about.

[jareg]

Talking of Smart people
I think he learned his lesson now

[Riskbreaker927]

haha.. pyramidal. Maybe he just refers to the fact that polygons are all rendered as triangles? But, even if he is, that's true of every 3D rendering engine in the history of mankind.