View Full Version : G400 MAX overclocking w/ MGA Tweak

23rd December 1999, 13:22
Finally, a great version of MGA Tweak for fine-tuning my G400 MAX.

I'm wondering about the WARP clock though. I've seen somewhere that it could let more fill rate speed by using PCI or AGP clock for WARP clock instead of the G400 CPU clock (ex: 33Mhz (PCI) instead of 150Mhz).

I've tried both and didn't see any differences. I've used 3DMark 2000 for testing.

I've overclocked my G400 MAX to near max speed. I need to cool down the G400 CPU (that damn fan/heatsink is worthless) before going higher (I know I can go about 5-8 Mhz more but it's too hot for now).

Does someone knows what is best about WARP clock and what it give as a result?

One other thing. What's the use of Memory Refresh Counter in the memory optimization settings?
I know I have to change it from defaults to keep clock monitoring at best but it doesn't seem to affect speed.

Thank you in advance!

MGA Tweak settings (up to now): System PLL= 517.50Mhz, Gclock=172.5Mhz (/3), Mclock=230Mhz (/2.25), WARP=172.5Mhz (/3) or 33.3Mhz (AGPPLL/2), manual Duty Cycle at G=0,M=4,W=0 , max memory settings (in order): 3,1,3,8,3,1,Fast,1,1,1,0.0,0.0,3009 .

23rd December 1999, 21:41
Sorry I don't have any answers for you, but I do have some questions ... How do you go about finding your optimal settings? Do you time/monitor 3DMark 2000 after modifying only one setting each time? Do you follow the documented procedure for memory optimization? Any other tips? I've glanced through the doc but I haven't gotten around to running the tweak utility yet. One thing I was concerned about is knowing what the current values of the write-only register(s) are. I didn't want to start to tweak without being sure that I could reset it back to its current state. I'm not sure I want to rely on someone other than Matrox to instruct me on the value of the write-only register(s).

24th December 1999, 00:13

There is no point changing the clock source of WARP clock. It should be clocked as graphics clock. The point for clock source selection is experimental purposes.


No matter what non-sense you've done to the Matrox hardware, as long as the RESET are pressed, everything's back to the factory defaults. I have done all kinds of non-sense to G200 and Mystique during the development of those utilities, that's how I bring things back to normal.

Just remember not to check the "Save Settings" when you're experimenting with MGATweak different options. If you accidentally save the settings, you can surpress MGATweak load from StartUp by holding SHIFT when you first see Windows boot. Then delete the registry key which MGATweak used to save settings.

24th December 1999, 07:45

It's very simple but needs a lot of patience!

I've started with the memory settings before increasing clocks. If you look in the MGA Tweak docs, there is a page that gives you a step-by-step SDRAM/SGRAM optimization.
I've simply tried the fastest setting for step 1 (1,Fast,1,1,1) and applyed it.
If the screen doesn't become garbled, go to step 2 and try decreasing the value by 1. apply. If screen isn't garbled, go to step 3... and so on.

When your screen become garbled, you know this isn't a good value. Normally, you'll have to reset your computer and try again using all the optimized values you entered in the preceding steps but leaving the value in the step you were doing as it was before changing it. Always try to use the lowest values for each.
Even if that happened, go to the next step and do the same thing. If there is a value that you can't decrease much because your screen gets garbled, that doesn't mean the other values can't be optimized either.

Don't forget step 7 (memory clock base). I was able to go all the way to 0ns but that could not be your case.

And by the way, this is for the clock you are working on. I mean by that that at first, I tried some values (wich were slower than what I said in my message) but I was still using 300Mhz system PLL clock. When I finally came to 517.50Mhz, I could change the memory values a bit faster by doing the same steps.

But even if after all that your screen is still clean, that doesn't mean that 3D is too. You'll have to test with some 3D benchmark or game (I used the demo in 3dMark 2000, the TechDEMO of Matrox, Quake 3 and Unreal Tournament), at the highest quality settings and at the fastest. Then, if you see some "snow", or some part of the screen being distorted once in a while, you'll have to change some memory settings up.
For me, I just had to change "Minimum RAS-to-CAS delay" and "Minimum RAS Precharge delay" by 1 up (back to 4). Then again, when I used 517.50Mhz clock, I put them back to 3 without any flickering or "snow".

That seems complicated but keep in mind that 2D (your desktop) and 3D are not the same so you always should try a 3D benchmark or game even if your settings are perfect for 2D.

Same thing for the clocks. It's a bit more complicated because you have to consider the duty cycle at the same time but besides that, you just increase a bit and try. If that works, try a bit more, and a bit more.
When it fails, try changing duty cycles up or down (down is faster but sometimes it's better to up a bit because a lot of distortion can happen at faster cycles).

If you don't want to crack your head at this, you try each one after the other with the fastest setting you can use and let it there.

I don't recommend going too high though , unless you have a way of cooling it down, 'cause the G400 cpu (and memory) gets REALLY HOT. (I had to change the fan that came with my G400 MAX with a much higher and bigger fan/heatsink to go beyond 517.50Mhz)

Hope I didn't get you more confused with all this...

2nd January 2000, 10:59
Thanks for your responses guys. I'll proceed with the overclocking now that the Y2K turnover has occured (wanted to make sure everything else is stable). Liew, you state that a reset will set the G400 Max back to its factory defaults. Do you mean that the board resets back to its internal hard-coded defaults or your utility will set the board back to the factory defaults as you understand them? Thanks for the clarification.
I'm not planning on changing my cooling as I hope the Max fan and my OEM Intel XEON case (http://www.liteonenclosure.com/products/ms440gx/ms440gx.htm) will be adequate.

3rd January 2000, 05:44

When the RESET button is pressed, MGATweak no longer gain control of the hardware. So the hardware will be set according to Matrox video BIOS. When Win9x starts up, Matrox Powerdesk will be the one that changes some settings. After this, only MGATweak will gain control, if it is put in the startup folder and instructed to load settings. If SHIFT is pressed and hold, MGATweak will be bypassed.

MGATweak does not physically make permanent changes inside the hardware. But it can have permanent effects if you misuse it.

3rd January 2000, 11:18
Thanks Liew. I understand. I thought you were referring to some sort of reset of the video card versus the system going through POST. I had also thought that you were flashing the BIOS with new defaults. You're clarification has me rest easier. Is there any documentation on what not to do in order to protect the Max from "misuse"? I assume I'm fine as long as I creep up each of the settings between testing.