PCI-E backwards compatibility AMD and Nvidia?

[manko]

I have an old Intel 945GC based motherboard with either a PCI-E x16 1.1 or 1.0a slot. I have used two PCI-E 2.0 cards in it and they both work fine (AMD 4670 and Nvidia GTX 260).

I recently picked up a new R9 270 and tried to install it, but the machine wouldn't even post. I have a solid 600W+ power supply, so that wasn't the issue. The fans started to spin up on everything, then it powered off and restarted without even getting to the bios screen.

Looking into the issue, it seems that the newer AMD cards may not work in older boards that are not at least PCI-E 2.1 compatible or higher. I found a post here that mentioned AMD 5xxx series and later may have trouble on old boards. I also saw some mention that newer Nvidia cards might have better backwards compatibility.

My motherboard hasn't had any firmware updates in years, so that's not an option and I don't want to replace motherboard, CPU and memory just to run a newer card. I already have another relatively recent Ivy Bridge machine, but I wanted to update the card in my old spare machine.

I returned the R9 270, but I wonder if there are any newer cards that would work instead. Are there any current lower end AMD cards which will actually work in an old PCI-E x16 1.1 slot that worked fine with PCI-E 2.0 cards? I'm not sure I should even bother looking into older generation used cards, since I read that cards going back to the AMD 5xxx series may have the same compatibility problems.

Are any current Nvidia cards (such as the 750ti) more likely to be backwards compatible with early PCI-E 1.1 hardware?

 

[nwo]

I had the exact same issue with my P67 motherboard. My 7 series cards work fine (7850, 7870, 7970) as well as my 5870 but my 270 would not POST. I popped it into my z87 and it worked fine.

I have used some 7 series cards (7790) and a 4870 in my super old socket 939 motherboard with the first generation of PCI-e slots but I have not tried anything newer than that. The only problem I did have though was that I could not run two PCI-e graphics cards at the same time in this board, even though my motherboard supports crossfire.

 

[el etro]

To your board you can Try a Nvidia GTX 560(is likely to function).

If you want more power you can try a GTX 660, maybe it works.

 

[Shmee]

Hmm, not sure if this will help, but interestingly enough I can run an xfx 7850 in a 939 board, works fine for mining. It would be way to CPU and memory bound for gaming though.

 

[manko]

Thanks for all the comments. Maybe I'll look into a 7850 that might work with my old board.

 

[nwo]

I think the entire 7 series are a safe bet. The newest AMD generation of GPUs do not seem to be very friendly or backwards compatible with old motherboards and older PCI-e slots.