Back when I started working on my first retro build (a 486 with muscles of steel), I had considered using the G450 as a 2D card, however, wanting to use the MS-DOS 6.22 + Windows 3.1 combination, I found myself limited in Windows to using the generic 256 color driver (Matrox had released Win 3.1 drivers for the G400 but not for the G450). So I looked for a solution: I had thought about modifying the G400 drivers (as mentioned, G450 is a simple die shrink of G400) however I found various negative experiences in this regard on the Internet and therefore I decided to give up.
Maybe whoever had tried to modify the G400 drivers to use them with the G450 had done something wrong, they didn't have enough experience.
For my build, I just thought, having a 4MB Millennium II available, that it would be enough for DOS and Win 3.1 and that in this way I would finish my build quickly and without any particular problems... and so it was... and so the project retro began 😁
From the technical specifications reported on the boards made by TechPowerUp what I said seems confirmed to me.
Then the fact that the video cards based on these chips have different capacities because they are equipped with a different number of RAMDACs, as well as different memories and commission buses, this is another matter.
If you want to make a comparison it's like between P3 Coppermine and P3 Tualatin, they are essentially the same CPU, only that the second one, having been built with a more efficient process, was able to scale up in speed and with the extra space freed up on the die it received more L2 cache 😁
That is impossible. G450 added a second ramdac and surely they wouldn't spare transistors on an unused 128-bit memory bus while they were at it.
Then the fact that the video cards based on these chips have different capacities because they are equipped with a different number of RAMDACs, as well as different memories and commission buses, this is another matter.
If you want to make a comparison it's like between P3 Coppermine and P3 Tualatin, they are essentially the same CPU, only that the second one, having been built with a more efficient process, was able to scale up in speed and with the extra space freed up on the die it received more L2 cache 😁
it is not another matter. Die shrink means taking the same die and making it smaller. Enlarging the L2 cache for example means at the very least rearranging the layout, necessitating a design effort.
If it would be just a die shrink without changing any internal registers and logic then there's no reason why G450 not work (after changing DID) with old drivers. But as there 2nd RAMDAC was added it would be reason that some internal logic was changed and that could break the compatability with drivers. If we would have datasheets (not just a brief tech. spec) of both chips then we can compare how it really differs but I didn't find any leaked document of Gxx series, all I have is Matrox MGA-2164W developer’s specification.pdf
So, now I have more knowledge about matrox cards than earlier, I took my G450 PCI again and I can try to modify the pins and overclock the memory to 200 mhz, obviously since the clock are ganged the core clock will follow.
It should be possible since the memory are rated for 5ns, what do you think?
I tested the card in windows 98, I confirm that overclocking with powerstrip makes the card slower and choppy (same behaviour as windows xp), I will try to use other utilities if possible and then try the pins overclock but I need to study it carefully.
So apparently the overclocking (with pins) quest is more difficult than I thought.
The standard frequency for the card as we know it's 115,20 for the core and 144 for the memory. Any overclock attempt with powerstrip slows the card down, any attempt with MGATweak leads to a completely messed up image.
What I found so far is the card has a System PLL clock of 279,00 mhz which is roughly the 115+144+20 (I don't know what the 20 difference is). If I overclock the card to 120-150 the system pll becomes 299,45.
The checksum is calculated as follow: all bytes sum modulo 256 = 0
According to the most informative matrox website, to overclock the pins of the g400 (which is incomplete) should be:
Altering the PInS - G400
If you want to increase the SCLK above your card's factory limits, first change the SCLK limit. The val […] Show full quote
Altering the PInS - G400
If you want to increase the SCLK above your card's factory limits, first change the SCLK limit. The value coded in PInS is actually 1/4 of the real one, so "75" means 300 and "90" means 360.
To change the SCLK and GCLK for 3D modes, edit the fields......(soon)
Also, if you want to overclock the nonMax to near-Max values, start with changing the memory control word at location 81. .....(soon)
The sclk seems high enough (150*4=600 which should be the combination between memory and core clock?).
The interesting value as pointed out seems the sclk which is 72 (72*4=288), my guess would be to increase the values of pins 56 and 57 to 75 and see what will be the frequencies with powerstrip (I do not consider MGATweak reliable).
Any suggestion is appreciated.
Success! I've been able to modify the pins and the new frequency is now 124/155! I did two tries, the first one I modified just the pin 56 and 92. It gave the new clock in dos but not in windows, then I modified every 72 in the file to 78, it gave the higher clock in both environment. Apparently there are differeent clocks for different modes. The performance are faster, it doesn't suffer the drawback of powerstrip overclock. I'm going to push it further, if anything goes wrong I will be able to revert to the old pins.
