VOGONS


First post, by adalbert

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I've been testing PCI version of Zotac GT520 with Pentium 3 1.4 GHz. It's not a great card, but has working H.264 video acceleration. Unfortunately PCI bus gets saturated easily and overall performance is not that good.

PCIe to PCI adapters obviously do exist, either as standalone devices, or embedded in graphics card like GT520 PCI, but they are limited by 133MB/s transfer of PCI slot. Is there a way to overcome this limit?

Would it be possible to:
1. Solder AGP connector to PCI-e to PCI adapter, so it will work as 66MHz PCI card in AGP slot, having 266MB/s transfer?

or
2. Remove GPU chip from PCB of non-native AGP card (which used PCIe to AGP bridge) and solder cables coming out of PCIe riser to appropriate BGA pads?

Last edited by adalbert on 2021-01-12, 22:52. Edited 1 time in total.

Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix
ISA Wi-fi + USB in T3200SXC: https://www.youtube.com/watch?v=WX30t3lYezs
GUI programming for Windows 3.11 (the easy way): https://www.youtube.com/watch?v=d6L272OApVg

Reply 1 of 18, by The Serpent Rider

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You can put AGP card in AGP-to-PCI adapter and then place it to PCI-to-PCI-E adapter. AGP-to-PCI-E adapters would require Nvidia or ATI bridges soldered on adapter, as probably noone else bothered to make such bridge chips.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 2 of 18, by adalbert

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PCIe 1x only uses a few wires, so I was thinking about doing something like this:

Designing a PCB for BGA chip would be very difficult, but this way existing AGP card could be used as a 'donor'.
I wonder if this would have a chance to work. Are there any 'cheap' AGP cards with PCIe bridges that noone cares about, so they could be used for such experiments?

The Serpent Rider wrote on 2021-01-11, 13:46:

You can put AGP card in AGP-to-PCI adapter and then place it to PCI-to-PCI-E adapter.

I want to put high-end (GTX series) PCIe card in AGP slot.

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Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix
ISA Wi-fi + USB in T3200SXC: https://www.youtube.com/watch?v=WX30t3lYezs
GUI programming for Windows 3.11 (the easy way): https://www.youtube.com/watch?v=d6L272OApVg

Reply 3 of 18, by The Serpent Rider

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Are there any 'cheap' AGP cards with PCIe bridges that noone cares about

GeForce 6600.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 4 of 18, by adalbert

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Okay, so that actually would be the one that was on picture.
I'm trying to find datasheet for NV43 chips or schematics for graphic cards, I didn't find anything easily accessible yet.
Here is something but I'm not able to download it, if anybody could help it would be appreciated.
http://vlab.su/viewtopic.php?f=48&t=18147
https://remont-aud.net/load/drugaja_apparatur … t/330-1-0-31057

Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix
ISA Wi-fi + USB in T3200SXC: https://www.youtube.com/watch?v=WX30t3lYezs
GUI programming for Windows 3.11 (the easy way): https://www.youtube.com/watch?v=d6L272OApVg

Reply 5 of 18, by The Serpent Rider

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Here's something related: https://hwbot.org/newsflash/4883_throwback_th … _to_pci_adapter

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 6 of 18, by adalbert

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Looks interesting, although it does the reverse thing. But maybe its bridge chip would be bidirectional.

Anyway, i am also thinking about different approach, so I looked up some info about these PCIe - PCI adapters:
https://www.amazon.com/StarTech-com-Express-A … 1/dp/B0037ECAM2

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They are using this bi-directional PCI-express - PCI bridge chip https://www.diodes.com/part/view/PI7C9X130
It can also function as PCI-express to PCI-X bridge.

Datasheet looks interesting:

Screenshot_2021-01-11 PI7C9X130 data Sheet - PI7C9X130 pdf.png
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Looks like this bridge chip could be configured to any operating frequency by simply jumpering some pins.
So, because AGP standard is superset of PCI, but running at 66MHz, I think it would be worth trying to use PI7C9X130 as PCI-e to AGP bridge. It would operate as PCI 66MHz card, but using AGP physical connector. In theory it should have twice the standard PCI bandwidth, and exclusive connection to AGP bus.

Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix
ISA Wi-fi + USB in T3200SXC: https://www.youtube.com/watch?v=WX30t3lYezs
GUI programming for Windows 3.11 (the easy way): https://www.youtube.com/watch?v=d6L272OApVg

Reply 7 of 18, by The Serpent Rider

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But maybe its bridge chip would be bidirectional.

It was part of the package for original PCI-E GeForce 6800GT/Ultra and Quadro cards, located on chip PCB.

In theory it should have twice the standard PCI bandwidth, and exclusive connection to AGP bus.

Proper AGP with GART still has noticeable advantage over PCI 66 Mhz (even if it's just AGP slot without driver), especially in later games, which push more geometry.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 8 of 18, by adalbert

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All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find PCI-E signals on BGA pads by probing them (that would be the only purpose of PCI-E 6600 card, because I can't find datasheets). Then I would carefully solder wires, ideally shielded and with matching lenghts to BGA pads on AGP 6600 and connect them to PCI-E slot riser. Maybe i could even dremel out the unnecessary parts of 6600.

That's not easy. But I managed to make PCI-E eGPU long time ago when enclosures were expensive by soldering wires to cannibalized ExpressCard PCB. And it did work, so maybe it would work here too. Seems like a lot crazier idea though. But not nearly as crazy as that https://youtu.be/46gNvDLgLdI?t=181

I would be really happy if it would work with only 1 x wiring connected, because I don't want to solder all 16 lanes only to see if it works at all... If it follows the specification, it should. If it has hardcoded support of certain NVIDIA GPUs, that would be more problematic.

/edit:
it would be easy to start with this: solder really short wires between that little goldfinger x1 connector and BGA pads, hotglue that part to the board and use the riser with extension cable. Seems too easy to be true though.

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Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix
ISA Wi-fi + USB in T3200SXC: https://www.youtube.com/watch?v=WX30t3lYezs
GUI programming for Windows 3.11 (the easy way): https://www.youtube.com/watch?v=d6L272OApVg

Reply 9 of 18, by scheiss_freak

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You might want to check out my AGP to PCI Adapter: Re: AGP to PCI adapters - any PCB designers here willing to make one?

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Although I created it to use 66 MHz PCI and PCI-X Gigabit Ethernet or SATA adapters in the AGP of a headless system it should work for your usecase, too.

Reply 10 of 18, by TrashPanda

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adalbert wrote on 2021-01-12, 22:11:
All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find […]
Show full quote

All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find PCI-E signals on BGA pads by probing them (that would be the only purpose of PCI-E 6600 card, because I can't find datasheets). Then I would carefully solder wires, ideally shielded and with matching lenghts to BGA pads on AGP 6600 and connect them to PCI-E slot riser. Maybe i could even dremel out the unnecessary parts of 6600.

That's not easy. But I managed to make PCI-E eGPU long time ago when enclosures were expensive by soldering wires to cannibalized ExpressCard PCB. And it did work, so maybe it would work here too. Seems like a lot crazier idea though. But not nearly as crazy as that https://youtu.be/46gNvDLgLdI?t=181

I would be really happy if it would work with only 1 x wiring connected, because I don't want to solder all 16 lanes only to see if it works at all... If it follows the specification, it should. If it has hardcoded support of certain NVIDIA GPUs, that would be more problematic.

/edit:
it would be easy to start with this: solder really short wires between that little goldfinger x1 connector and BGA pads, hotglue that part to the board and use the riser with extension cable. Seems too easy to be true though.
Pg5L0.jpg

I know this is old but both GPU cores on the GPUs are the same, the AGP card has a PLX PCIe to AGP bridge chip on the back of it that takes the PCIe signals from the GPU die and translates them to AGP bus signals, its not the GPU core you need to probe on the AGP card but the PLX chip. I dont know if they ever released a data sheet for the PLX chips but its possible there is one out there.

In a sense what you are trying to do here is re-create the PLX chip ..so pretty much reinventing the wheel that already exists to put a PCIe GPU into an AGP slot.

Reply 11 of 18, by LSS10999

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TrashPanda wrote on 2022-06-28, 14:56:
adalbert wrote on 2021-01-12, 22:11:
All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find […]
Show full quote

All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find PCI-E signals on BGA pads by probing them (that would be the only purpose of PCI-E 6600 card, because I can't find datasheets). Then I would carefully solder wires, ideally shielded and with matching lenghts to BGA pads on AGP 6600 and connect them to PCI-E slot riser. Maybe i could even dremel out the unnecessary parts of 6600.

That's not easy. But I managed to make PCI-E eGPU long time ago when enclosures were expensive by soldering wires to cannibalized ExpressCard PCB. And it did work, so maybe it would work here too. Seems like a lot crazier idea though. But not nearly as crazy as that https://youtu.be/46gNvDLgLdI?t=181

I would be really happy if it would work with only 1 x wiring connected, because I don't want to solder all 16 lanes only to see if it works at all... If it follows the specification, it should. If it has hardcoded support of certain NVIDIA GPUs, that would be more problematic.

/edit:
it would be easy to start with this: solder really short wires between that little goldfinger x1 connector and BGA pads, hotglue that part to the board and use the riser with extension cable. Seems too easy to be true though.
Pg5L0.jpg

I know this is old but both GPU cores on the GPUs are the same, the AGP card has a PLX PCIe to AGP bridge chip on the back of it that takes the PCIe signals from the GPU die and translates them to AGP bus signals, its not the GPU core you need to probe on the AGP card but the PLX chip. I dont know if they ever released a data sheet for the PLX chips but its possible there is one out there.

In a sense what you are trying to do here is re-create the PLX chip ..so pretty much reinventing the wheel that already exists to put a PCIe GPU into an AGP slot.

I'm not sure if those proprietary AGP-PCIe bridges (nVidia BR02/HSI, ATI Rialto) were really made with PLX's technologies... but still, these bridge chips were made specifically for the cards they intended to use on.

For a "general purpose" PCIe-AGP adapter that would work for all PCIe cards, one would need a new design. But I'm curious how much bandwidth could an AGP x8 slot practically provide on the PCIe side?

For the opposite direction, some motherboards during the AGP to PCIe transition period managed to find ways to allow AGP cards to be connected to PCI or PCIe but from what I read these slots were not generic and only a finite amount of cards were supported according to their vendors.

On the other hand, there are already cards leveraging PEX8111 to allow PCIe cards be connected to PCI, and it seems to work with just any device (including NVMe SSDs).

Reply 12 of 18, by TrashPanda

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LSS10999 wrote on 2022-06-29, 01:14:
I'm not sure if those proprietary AGP-PCIe bridges (nVidia BR02/HSI, ATI Rialto) were really made with PLX's technologies... but […]
Show full quote
TrashPanda wrote on 2022-06-28, 14:56:
adalbert wrote on 2021-01-12, 22:11:
All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find […]
Show full quote

All right, so to get proper AGP bridge working i guess that I could get 6600 PCI-E and 6600AGP, desolder both BGA chips and find PCI-E signals on BGA pads by probing them (that would be the only purpose of PCI-E 6600 card, because I can't find datasheets). Then I would carefully solder wires, ideally shielded and with matching lenghts to BGA pads on AGP 6600 and connect them to PCI-E slot riser. Maybe i could even dremel out the unnecessary parts of 6600.

That's not easy. But I managed to make PCI-E eGPU long time ago when enclosures were expensive by soldering wires to cannibalized ExpressCard PCB. And it did work, so maybe it would work here too. Seems like a lot crazier idea though. But not nearly as crazy as that https://youtu.be/46gNvDLgLdI?t=181

I would be really happy if it would work with only 1 x wiring connected, because I don't want to solder all 16 lanes only to see if it works at all... If it follows the specification, it should. If it has hardcoded support of certain NVIDIA GPUs, that would be more problematic.

/edit:
it would be easy to start with this: solder really short wires between that little goldfinger x1 connector and BGA pads, hotglue that part to the board and use the riser with extension cable. Seems too easy to be true though.
Pg5L0.jpg

I know this is old but both GPU cores on the GPUs are the same, the AGP card has a PLX PCIe to AGP bridge chip on the back of it that takes the PCIe signals from the GPU die and translates them to AGP bus signals, its not the GPU core you need to probe on the AGP card but the PLX chip. I dont know if they ever released a data sheet for the PLX chips but its possible there is one out there.

In a sense what you are trying to do here is re-create the PLX chip ..so pretty much reinventing the wheel that already exists to put a PCIe GPU into an AGP slot.

I'm not sure if those proprietary AGP-PCIe bridges (nVidia BR02/HSI, ATI Rialto) were really made with PLX's technologies... but still, these bridge chips were made specifically for the cards they intended to use on.

For a "general purpose" PCIe-AGP adapter that would work for all PCIe cards, one would need a new design. But I'm curious how much bandwidth could an AGP x8 slot practically provide on the PCIe side?

For the opposite direction, some motherboards during the AGP to PCIe transition period managed to find ways to allow AGP cards to be connected to PCI or PCIe but from what I read these slots were not generic and only a finite amount of cards were supported according to their vendors.

On the other hand, there are already cards leveraging PEX8111 to allow PCIe cards be connected to PCI, and it seems to work with just any device (including NVMe SSDs).

I have a feeling that PCIe to PCI is less complicated than PCIe to AGP, and yes I dont believe its PLX but thats a word people understand when referring to these bridge chips, much like you knew exactly what I was talking about even if the name was not totally correct.

Reply 13 of 18, by LSS10999

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TrashPanda wrote on 2022-06-29, 01:26:

I have a feeling that PCIe to PCI is less complicated than PCIe to AGP, and yes I dont believe its PLX but thats a word people understand when referring to these bridge chips, much like you knew exactly what I was talking about even if the name was not totally correct.

From what I could see on the surface, PCI and PCIe do not appear too different to the software/OS. According to Wikipedia PCIe preserves backwards compatibility with PCI at software level.

Actually there's another PLX chip called PEX8114 which can be used in a similar fashion as PEX8111. It can convert a PCI-X slot (the longer 64-bit PCI slot usually seen on old server motherboards) to PCIe x4 and vice versa.

Unfortunately, I'm yet to see anyone making such adapters using that bridge, probably because PCI-X is generally uncommon compared to PCI.

Reply 14 of 18, by TrashPanda

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I have a Matrox Parhelia PCI-X that uses a PCIe to PCI-X PLX bridge chip on it, I have a feeling that 64bit PCI-X isn't that different from PCIe under the hood just PCI with more data/power lines.

Reply 16 of 18, by scheiss_freak

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I‘d be lying if I said I haven’t tried it. And this combination of parts at least posts.

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Reply 18 of 18, by LSS10999

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scheiss_freak wrote on 2022-07-28, 20:24:

I‘d be lying if I said I haven’t tried it. And this combination of parts at least posts.

Good to hear this combination posts fine. Is that PCIe adapter based on PEX8111/PEX8112?

These PCIe adapters appear to be more compatible, so one probably could use the AGP port for something other than a video card this way.