[LinuxBIOS] different versions of the GA-M57SLI-S4 (PLCC vs SPI)

Harald Gutmann harald.gutmann at gmx.net
Thu Jan 10 00:31:31 CET 2008

Am Sonntag, 2. Dezember 2007 05:48:23 schrieb Peter Stuge:
> On Sat, Dec 01, 2007 at 07:46:14PM -0500, Richard Smith wrote:
> > CS# from the IT8716F is routed up to R509 which is a zero ohm
> > resistor.
> >   If this resistor is in place then CS is hardwired to CS# on U5
> > which is the SPI chip that's loaded.  If you pull R509 then the CS#
> > to both chips are free to be selected by (unloaded) Q2,Q43,Q4, and
> > Q5 + resistors but I don't have the configuration mapped out.
> They would be part of Gigabyte's patented hardware BIOS failover
> technology I suppose.
> Q4-3 and Q5-3 are both connected to the superio side of R509, so the
> emitter if using PNP transistors.
> Traces from Q4-1 and Q5-1 both run toward the flash chips so they
> would be the collector.
> Q4-2 and Q5-2 the base, with R91 before Q4 and R90 before Q5. The
> other side of R91 goes to R389 which then goes to Q43-2. The other
> side of R90 goes to R86 which then goes to Q2-2.
> There are some vias on the traces between R{90,91} and Q{4,5} so they
> are connected to something else as well. (But what?) There are also
> vias on traces between R{86,389} and Q{2,43}.
> Q43 and Q4 are driven at the same time, through R389 and R91
> respectively. I wonder what the purpose of Q43 and Q2 is.
> The pinout does indeed match e.g. a BC847 PNP transistor in SOT23
> package.
> R89 is between Q4-1 (U5-CS#?) and a power net, so would be the
> pull-up for when Q4 is not driven to select U5.
> There is certainly a corresponding resistor for Q5-1 but there's only
> a via from the Q5-1 trace so it would have to be tested. My guess is
> R130 (directly south of R129) since it's other end goes to U9-CS#.
> > It does not look like there is any easy way to re-enable switching
> > between the SPI chips since you have to load several missing parts.
> The switch mod can be simplified to use existing pads and no pins
> have to be lifted from the flash chips anymore.
> 1. Remove R509.
> 2. Populate R89 and R130 with 10k or 100k pull-up 0402 resistors.
> 3. Solder the switch common to Q4-3 and switch between Q4-1 and Q5-1.
Confirmed. But not with SMD Resistors.

First I removed the R509.
As there are connections from R89 Left to U5 VCC; from R89 Right to U9 CS#; 
from R130 Left to U5 CS# and from R130 Right to U9 VCC I soldered normal 100k 
resistors between U5 VCC and U9 CS# and between U5 CS# and U9 VCC.

Here are two photos of my new mod:

I know, that these cables to the sockel are not really fine, but i had no 
other solution for mounting the sockel on the mainboard and it works fine!

I added a sockel for the SPI-chips to be able to change the bios chip in an 
easy way. If someone is interested which sockels these are, they are 
manufactured by WELLS-CTI and have the part number 652C0082211-W003.
I payed about 8€ per part, and that sould be about 10$, without shipping 
costs. The distributer for these sockels was http://www.bfioptilas.com/.

(PS: thanks to Mr. A. v. Heydwolff for organising these sockels.)

> Of course this assumes that soldering 0402 resistors is considered
> simple, which isn't likely true unless you're good at SMT soldering.
A friend of mine helped me with the soldering, but he said that it is nearly 
impossible to solder these resistors without industry-equipment.

> > I'll probably just end up soldering on a 2nd chip and then wiring
> > the CS# pins up to a switch like the other mods did.
> Of course there could be some timer thingy to do failover, but I
> think manual control is best. I think the spring-loaded switch is
> as useful as any mechanism in this case.
> //Peter

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