3DFX Voodoo5 5500 works on PCI-Express !!

[m14radu]

mee too, but without luck.
I think that the only way is to subscribe to PLX, and then we can get the datasheets and the SDK too.

[voodoo5k6]

http://www.alldatasheet.com

[goriath]

Originally posted by voodoo5k6

http://www.alldatasheet.com

This was the first attempt we all did, I suppose[]

BTW, here the DATABOOK:

We would have noticed that this bridge chip is produced by PLX Technologies, but the product's name is officially PEX8112:D

[voodoo5k6]

I make some test with Startech PCIetoPCI adaptor. Pericom Chip.

Motherboard : P35 DS4 ( intel q6600 2,4 ghz 4Gb ddr2 RAM )

With 3dmark2001se :

On PCIexpress16x slot , I've got 3340 marks. ( pcietopci not modded, v5500 pci not modded )



On PCI simple Slot, I've got 3065 marks.



Conclusion :

>I think this adaptor put 66 mhz when you connect V5500 pci on it with PCIexpress.
When i connect v5500 pci on PCI slot i have less marks.

[m14radu]

This is normal.
The PCI slot will operate @33Mhz even if you mask the pin49b on the voodoo5.
Masking the Pin49b will help only in combination with the pcie2pci adapter..only in this combination 66Mhz are possible.

Let's come back to our PLX8112
I've read the datasheet of the PLX and the only question now is:
How to set M66EN high ?

[m14radu]

Nobody knows how to set M66EN high ?


@osckhar: can you please check if the pin49b on your PERICOM adapter is grounded ?

Thanks mate

[goriath]

Originally posted by m14radu

Nobody knows how to set M66EN high ?


@osckhar: can you please check if the pin49b on your PERICOM adapter is grounded ?

Thanks mate

I am thinking about this issue.

On Voodoo5, pin 49b acts on M66EN settings. Masking this pin affects 66MHz mode on the Pericom bridge (from what I heard), while it doesn't on the PLX bridge. Maybe for the different bridge's designs.

To ENable 66MHz Mode (M66EN) we must put M66EN on High; reading the PEX8112 databook, this is not the only condition:





Assuming we put M66EN on High, PCLKO will be setted to 0011b because is it for default, but PCLKO62SEL# must be on High as well or left disconnected at least.

M66EN and PCLKO62SEL# are D10 and C2 balls respectively on the chip ball grid array; desolder the C2 (disconnect PCLKO62SEL#) would be a first step, but near impossible unless a huge and deep adapter's rework.

Last but not least, I am thinking about BUS bandwidth.

PCI66 standard allows 266MB/s data transfert (4Byte*66.6MHz)
PCIe x1 standard allows 250MB/s data transfert (since 10bit encoding, @100MHz)

One of the reasons this bridge can select 62.5MHz instead of 66MHz, could be jitter frequency; indeed 4Byte*62.5MHz=250MB/s, same bandwidth as PCIe x1 specs.

In any case we have a little but still present bottle-neck that cuts off about 16MB/s

Supermicro's adapter probably can use the full PCI66 bandwidth, but still I find it uncomfortable and no user-friendly due its design.

PLX makes also the PEX8114 bridge chip that supports PCI 3.0 (32/64bit @33/50/66MHz) and PCI-X 1.0 (64bit @66/100/133MHz) specifications, forwarding to PCIe interface up to x4 that for the aim is more than enough.

I found an adapter equipped with this bridge:

[m14radu]

Thanks for the informations goriath !

I read it carefully and search on the PCB the position of the C2.
Unfortunately the pins on the back side are not on the same position as from the front side.
This make almost impossible to find out the pin C2.



Do you have an ideea how to find it ?

Did somebody else manage to find out the position of the C2 ?

One ideea is to write an email to PLX, mayb they can help us with some hints

[goriath]

In FBGA designs, pins (balls) are located underside the BGA chip, like VSA-100 for example.

So desolder C2 means desolder the entire bridge first, than reball it exept for C2 and finally resolder the chip on the adapter through a good hot air station at least, or IR station would make it professionally.

[m14radu]

oh, i can't do this

i thought there is a connection vissible on the card back that can be changed.

[goriath]

Originally posted by m14radu

oh, i can't do this

i thought there is a connection vissible on the card back that can be changed.

Ya, it isn't a easy task.

BTW, still remain the question why the bridge won't set itself @66MHz if the graphics adapter installed is 66MHz capable.

[m14radu]

Pin C2 i believe...

[goriath]

Originally posted by m14radu

Pin C2 i believe...

If was like you said, this adaptor wouldn't support 66MHz, although it has this bridge.

I suppose that ball D10 (M66EN) is grounded for 33MHz operation.

[m14radu]

it's possible that D10 is grounded via a resistor, right ?
on the back side are some resistors ...one of them maybe connect the D12 to ground...
it's there a possibility to find that out ? ( whithout to unsolder the bridge )



btw:

look at this settings:



is the Bit 5 coorect initialized ?
Default value is 1, but the status is 0...why ?
The Bit is Read only.

[goriath]

Originally posted by m14radu

it's possible that D10 is grounded via a resistor, right ?
on the back side are a lot of resistors ...one of them maybe connect the D12 to ground...
it's there a possibility to find that out ? ( whithout to unsolder the bridge )

Yes, I was thinking the same.
We could try to analize the tracks eventually seeking for a resistor, but actually I don't own any of these adapters[:I]