On Sep 26, 2012, at 7:50 AM, Nabil wrote:
I will buy a PC card. I have the required equipment to do it (PC and
PowerMac G4), found this explaining how to do it:
http://web.archive.org/web/20100522054343/http://www.darkness.uklinux.net/
Is it accurate?
Yes, although I've never gone as far as soldering a new ROM chip onto
a card. If the ROM is the smaller size, there is a special reduced
size ROM file that works in the smaller ROM chips.
Also, there can be some problems with the speed of the physical VRAM
on the PC cards which in rare circumstances can cause video glitches.
This can be corrected by using a custom ROM file, or adjusting the ROM
clock in software using ATIcellerator II. I prefer the custom ROM if
this is necessary. The Mac Radeon 7000 only came in a single version
which has 50ns (ns=nano second) VRAM chips, which correspond to a
clock rate of 183 MHz. The Mac ROM normally sets the GPU & Bus speeds
to 183 MHz.
The PC cards came with a variety of VRAM chips that vary from a slow
of 75ns, but also come in 70, 60, 50, 40, or 35ns speeds. If your card
has chips that are SLOWER than 50ns (i.e. 75, 70, or 60ns) there will
be video glitches & artifacts because the clock rate of 183 MHz will
be too high for these slower chips. Sometimes it's not a problem, it's
like overclocking the slow chips, and sometimes they overclock OK, but
if not, you can either create, or download, a slower ROM. There's a
166MHz ROM common for download that will normally fix this issue.
The VRAM chips have a # printed on them, and there is a "-" at the end
of this # followed by the speed in ns, so the number would be
something like ############-50 if the chip was a 50ns chip, and
############-35 if it was a FASTER 35ns chip. Since 50ns is the
standard Mac chip, it always works. If the chips are FASTER (i.e. 40
or 35ns) then you can safely overclock the card to a higher clock
rate, probably 200MHz, or maybe even 225MHz. There's no need to
overclock, the faster chips will work perfectly with the standard
183MHz Mac ROM, they will run cooler and effectively be underclocked.
Most likely you won't need to deal with this aspect of custom clock
rates and can simply flash the card with a standard Mac ROM and it
will function fine.
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