@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.

Hey!

I'm in need of an AGP-to-PCI(-X) adapter to insert AGP video card into my DEC Alpha DS10 machine w/out AGP port. Does anybody have one for sale? I can do some testing with the most recent OpenVMS if would be needed 😀

Thanks!

-nismo1968

sdz wrote on 2024-01-27, 13:05:

@Kahenraz
I made a page for it and uploaded the files : http://sdz-mods.com/index.php/2024/01/27/v5-5 … 00-agp-pci-psu/
Gerbers, as well as sch/pcb, so one could modify it if needed.

Just doing research at the minute and found your adapter.
I don't see any logical reason for your design to not work shifting agp signals up/down 1.5v/3.3v

Do you?

It's related to the last thing in my sig 😉
It'd be nice to have a bx that can fit every agp card ever and not blow them up.

(Yes, I know 2x speed only, and I've found out that p.8v was never really used in practice.)

Also, SN74CB3Q16245DL are functionally the same as the ones you used, right?

You're right, it should work fine for 1.5V operation. However, I really don't think any of those 1.5V cards will actually work, as they are too new, and they will be running with only the PCI part of the AGP bus. I doubt anything will work after installing a driver for such a video card. DOS operation should be fine.
Yes, SN74CB3Q16245DL seems equivalent in functionality with SN74CB3T3245.

Ah cheers. How about these?
https://www.ti.com/product/LSF0102

The idea is actually an 8x >2x "adapter" as it were.
8x cards should still operate at 2x,but the voltage can be a problem.

Very early days, but maybe a new 440bx board design. I copied the reference schematic. Just the schematic so far.
You might find it interesting.

Re: The thing no one asked for: KICAD 440bx reference schematic

Those might works as well, but be sure to read the datasheet. Level shifters can be really tricky sometimes.

Oh, sorry, I get it now. So it's AGP to AGP, not AGP to PCI. That could work with new cards.

Interesting project! A 440BX MB is also something that I plan to do, maybe next year 😀

It's next year..
Pm 😉

sdz wrote on 2020-09-23, 17:51:

Something like this? […]
Show full quote

Something like this?

The attachment 20200624_184104.resized-1024x365.png is no longer available

The attachment 20200624_1841042.resized-1024x365.png is no longer available

Even made a bracket for the V5 😀

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I designed it a couple of months ago, AGP 1.0 1x (3.3V only), 4 layer board with uninterrupted ground plane under PCI signals, properly terminated unused AGP signals, 12V PCIe power input, 3.3V/5V switching power supplies which can deliver more power than the AGP specs require, separately filtered AGP VIO, high speed level shifters, it can work in any 3.3V/5V PCI slots, 33/66MHz jumper (if the mobo supports PCI 66MHz ofc), 2 fan headers with support for 5V/12V 3pin/4pin fans and adjustable PWM.

I created an account just to say that this card is just gorgeous - elegant simplicity

I’m still wanting to buy one of sdz’s adapters.

Could use it for several of my builds

@sdz

hello!

i wanna this "PCIe x4 to PCI 32 bit bridge" adapter -)

available for sale?

I'd like to see a single PCB product which lets people use a half-height PCIe graphics card in an AGP 4x/8x slot. This would likely require some type of driver modification. Nonetheless, this could extend the life of some of those last generation AGP 8x motherboards, like those with an AM2 processor which already have their PCIe slot utilised by another expansion card.

To get proper PCIe Speeds in AGP you will need a Rialto bridge or HSI. The approach that was chosen by sdz was a PCIe to PCI converter, which equals to AGP 1x speed (AGP is PCI in its core). That's not a trivial thing unfortunately..

feipoa wrote on 2026-01-13, 13:44:

I'd like to see a single PCB product which lets people use a half-height PCIe graphics card in an AGP 4x/8x slot. This would likely require some type of driver modification. Nonetheless, this could extend the life of some of those last generation AGP 8x motherboards, like those with an AM2 processor which already have their PCIe slot utilised by another expansion card.

The problem with half height cards in full height slots is that the top of the rear I/O bracket is rotated 180 degrees, if I remember correctly. You would still need to 3D print out a custom bracket to replace it.