Overclocking my G400 MAX

[Ad B]

Figures.

The card overheats running 2D, but not 3D. After a while on the desktop I had an artefact following my mouse!

I'm using 180/225.

I'll try you setting. Prob is, I don't seem to have the nack for running with the Mem with a 2.25 divider.

[Neil]

The highest I got my g400max was 173/216 (432pll & 2.5/2/2.5). I think my problem is my overclocked AGP bus of 89mhz.
But, on my p3-550e @ 733mhz, my G400max runs fine at agp 2x. So I really can't complain.

[WaR-ped]

I think it depends on the card.. i just tried the 702 config... it runs fine for me. i'm also running a high agp....93mhz. maybe i am just lucky...

[mkaresh]

A few comments:

1. If you're running gclock and mclock the same, why mess with a 3 divider? Why not use a 1 divider even? Doesn't it make sense to use the lowest divider you can?

2. The default settings in the SGRAM optimizer are NOT those used by the Matrox drivers automatically. This is clezrly stated in the literature (readme?) for MGATweak. When I ran the "optimal" settings suggested in that literature, which I've noticed that many people do use, my performance as measured by 3dmark actually declined. So the settings used by the Matrox drivers must be quite fast.

3. In my numerous tests, I have noticed no impact of overclocking the AGP bus on the ability to oc the G400 itself.

4. Why uncheck auto for duty cycle correction? What should the setting be? What is this for anyway? I usually run stock, but when I do oc the card I use 432/2.5/2/2.5 for 173/216.



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PIII 500e @667
Soyo SY6BA+IV
Iwill Slotket II
G400 32MB Max
Nokia 445Xi 21"
and POS 14"
Aureal Vortex Superquad
128MB PC133
IBM DPTA 20.5GB 7200rpm
Toshiba 8/40 DVD

[Dyre]

Just rememebr that some of those dividers dont work right, and it will tell you it did, even though it didnt. Just a warning.

BTW if you leave duty correction checked you can max out the PLL and everythoing. its pretty funny. just doesnt do anything. great example of MgTweak not working right and mis-reporting

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PIII 450 @ 504
generic BX motherboard
G400 MAX : )
Maxtor 13 gig UDMA 33
Maxtor 13 gig UDMA 66
Creative 36x CD-ROM
HP 2x2x6x CD-RW
64 megs PC100 RAM
128 megs PC133 ECC RAM
NetGear 10/100
Soundblaster 32 AWE
Diamond SupraExpress 56k
Logitech Wireless Desktop (best $50 ive ever spent)
1 92mm Sunon Fan
4 80mm Sunon Fan's

[Kurt]

mKaresh,

I tried running the card with multipliers of 1.00, but the only effect is that it crashes the system immediately...Right now the card is set to 230 core and 256 mem with a PLL of 576 and divs 2.5/2.25/2.5. I am trying to max out the fillrate, but can't get past the 325-330MT. The score is even lower if I leave the Powerdesk settings. I'll try the 5.50 drivers to see...

[kjliew]

It should be noted that MGATweak does have limitations. The official specs from Matrox states that the system PLL limit lies somewhere in 310MHz. When trying to overclock, don't expect insane results on system PLL of over 500MHz. The N,M,P parameters fed to the PLL may no longer be valid.

The best rule for MGATweak is overclock then test. If you don't get an increase in fillrate (...at least), your MGATweak settings may not be valid as what it is shown.

[mkaresh]

So if I set duty cycle correction manually, what should I set it to?

Again, PLL 432 with 2.5/2/2.5. Auto = 11.

Thanks.

[Kurt]

Kjliew,

do you know where I can get the Duty Cycle table?
I am trying to figure out how exactly the memory has to be synchronized to the core.
Second question, how can I derive the best memory refresh counter from the speed of the memory.

[Kurt]

Also, is there a way for you to extract the memory settings' values used by Powerdesk?

Thanks

[kjliew]

mkaresh,
I would suggest you to stick with the G400MAX settings. There are no further explanation provided by Matrox chip specs, other than saying that duty cycle correction are needed to maintain 45/55 after going through certain dividers.

Kurt,
The duty cycle table is included in Matrox G400 chip specs. You must registered with Matrox before you can get access to it. I doubt whether Matrox own G400 overclocking utility would ever follow that rulez.... If you're interested to try out, you can use Matrox Tweak for overclocking and use MGATweak to check whether there is any changes in the duty cycle. Moreover, the duty cycle table has some ambiguities as well, if you look carefully.....

Being an outsider, I don't have much privilege of accessing G400 internals, other than the developers' chip specs, which I would say it's already a courtesy from Matrox. From the chip specs point of view, there is no way to read back the SGRAM settings. But from my experience in electronics design, there must be an alternate/test mode, which allow all read-only or write-only registers to be read/write as well. Such information is highly confidential.