@underage
I would like to share the files of the next revision, but I don't know when I'll do that.
The current revision has some components that are really expensive, and there were a few issues left to be fixed.

@anthony
That's true, I mostly designed this to use V5 5500 AGP cards in newer systems. The oldest MB I tested the adapter in was a socket 478 one, and it works fine. For older systems, yes, a pci-pci bridge would fix any issues.

dm- wrote on 2024-01-05, 03:43:

Is it possible to have a pcie to agp adapter card? to put the pcie card in to agp slot?

prices for agp cards went up, but at the same time, pcie versions are still cheap.

i have pcie to pci adapter from aliexpress and everything works well, 7800,8800,9400 and even gtx480, but the pci bottleneck is making everything not so good.

I am in too for making of an adapter which allow to use a PCI Express x16 graphic card in AGP slot.

@ sdz
Are you going to aim sometimes for such adapter please?

@Rabanik
I don't plan to make such an adapter. It should be possible to make such a thing using PI7C9X130 PCIe to PCI bridge in reverse bridge mode, and only the PCI part of the AGP bus.
If you would like to make such an adapter, drop a PM, I can provide my PI7C9X130 schematics (PCIe to PCI adapter), and also reference ones with reverse bridge mode, as well as other tools.

"If you would like to make such an adapter, drop a PM, I can provide my PI7C9X130 schematics (PCIe to PCI adapter), and also reference ones with reverse bridge mode, as well as other tools."
I'm afraid it is not in my strength. But there will a big performance drop, right?
Wouldn't be better to salvage the HSI bridge chips from old nVidia cards?

It will probably be worse than agp versions of the same or similar cards as the agp features won’t work.

It will still be at least 66 mhz pci thru put so at least there is that.

It’s possible paired with super fast gpu you may be able to exceed available agp cards despite the interface being slower than agp but perhaps in not all aspects.

Suggest doing the test on a 66mhz pci system before building the adapter, see if it seems worth it.

already did some tests
i have a supermicro desktop board based on server e7505 chipset, model x5dal-tg2.
so it has a pci-x slots which can work as a pci-66mhz. (266mb)

anyway... paired with 3.2ghz server xeon gallatin cpu and pcie->pci66 radeon 5770 scored 26k 3dmark 2003 . same card in pcie and with c2d scored 47k.
geforce cards in 3dmarks just does not likes pcie->pci. in games it depends.. some game love geforce, some radeon.

in most games this thing will work pretty good, even up to full hd resolution. later games, more issues, gta iv struggling heavy from low pci bandwidth.

Rabanik wrote on 2024-05-12, 12:48:

"If you would like to make such an adapter, drop a PM, I can provide my PI7C9X130 schematics (PCIe to PCI adapter), and also reference ones with reverse bridge mode, as well as other tools."
I'm afraid it is not in my strength. But there will a big performance drop, right?
Wouldn't be better to salvage the HSI bridge chips from old nVidia cards?

Be it HSI or Rialto (ATi counterpart), you need to first find their datasheets as well as other documentations useful for making such designs. I don't think they are available in an accessible way at the moment.

On the other hand, a DisplayPort capable PCIe video card will definitely work well even behind a PCIe -> PCI adapter, as you can set high desktop resolutions and refresh rates that were never possible with existing AGP video cards. Performance in game and other use cases will be limited by PCI's bandwidth, however.

LSS10999 wrote on 2024-05-14, 11:50:

Rabanik wrote on 2024-05-12, 12:48:

"If you would like to make such an adapter, drop a PM, I can provide my PI7C9X130 schematics (PCIe to PCI adapter), and also reference ones with reverse bridge mode, as well as other tools."
I'm afraid it is not in my strength. But there will a big performance drop, right?
Wouldn't be better to salvage the HSI bridge chips from old nVidia cards?

Be it HSI or Rialto (ATi counterpart), you need to first find their datasheets as well as other documentations useful for making such designs. I don't think they are available in an accessible way at the moment.

On the other hand, a DisplayPort capable PCIe video card will definitely work well even behind a PCIe -> PCI adapter, as you can set high desktop resolutions and refresh rates that were never possible with existing AGP video cards. Performance in game and other use cases will be limited by PCI's bandwidth, however.

Thank you dm- for the tests. Fortunatelly I have no such server motherboard.
My point is having of a multipurpose gaming PC machine (DOS/W9x/XP) with various graphic cards/standards (included Vo0doo cards) and where every used PCI and AGP slot really matters. So for example you can use combine Radeon X850XT AGP and GeForce 7800 PCIe reduced to PCI or to AGP or vice versa. So both type of adapters where you reduce PCIe graphic card to AGP or to PCI is really desired.