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The primary and secondary PCI Express slots on my motherboard, 16x and 8 x respectively, seem totally shot.

Board has a 16x, 8x, and 4x slots and right now both the 16x and the 8x will not work. The 4x works but, obviously, its seriously hampering the video card installed there. Board is an Intel Desktop D975XBX2

Basically what happens is I try installing a video card in the other two slots and the system won't even BEGIN to start up. Doesn't even get to the BIOS, absolutely nothing. Monitor doesn't register any activity and the computer itself acts as if there is a short or something i.e. doesn't do anything whatsoever though the drives do turn on.


Weird thing is when I was messing with the 16x slot I actually got it to boot up normally, but only was able to twice and it all went to hell again. The second time I made sure not to touch anything on the hardware after it started to boot, just told it to restart in windows. Bam, problem is back.

Is it possible a bad PSU could be responsible for this? I mean, the slot obviously is capable of working since... well, it has. This is further supported by botht he 8x and 16x slots simultaneously not working. Maybe the PSU can only supply power to the 4x slot and not the 8x and 16x?

I have no idea... Someone please help before I put my fist through my monitor in nerd rage.

There exist what is called DMA Failure. I suggest you look it up in Wikipedia. It's kind of difficult to verify, you have to remove and reinstall all your peripheral devices one at a time. Did you try flashing/resetting your BIOS? What type of mainboard do you use? What is your system's configuration? Did you try installing your video card on another system?

Well, any time I have had the video card in those two slots it has refused to boot save for those two incidents. For most of these the only thing installed was the video card, no peripherals at all including mouse and keyboard. Unfortunately I don't have access to any other computers with PCIe slots so I can't test the card itself, but I doubt it's the card since it works fine on the 4x slot.

It's an Intel Desktop D975XBX2 and i've tried chipset drivers, BIOS updates, everything I can think of.

I haven't tried resetting the BIOS and starting from scratch though, not sure how to do that. What steps would I take for that?

Ok so more info.... I'm not too good with technology but I know how to solve problems.


The difference between the 16x and the 8x is that they are routed (sorry if that's not the correct term) through the MCH while the 4x (the one that works) is routed through something else.

Now, since I have been able to start the computer up in the 16x slot twice now I KNOW that it at least has the capacity to work, just not consistantly. This suggests that something is not broken entirely.

Additionally it suggests something is wrong with the MCH. However, since the memory works just fine (I would assume the Memory Control Hub controls... memory) and nothing else is experiencing problems but the PCIe slots CONNECTED to it, I can only assume that something is happening between the PCIe slots and the MCH but not something permanent (i.e. damage) since it has on two occasions actually worked.

The only logical conclusion I can make is that there is a short between the MCH and PCIe slots.

How does this sound to you guys?

The question remains, however... how would this just happen randomly??

Bah, didn't work

Really? Nobody else has any suggestions?

This is the weirdest thing i've ever seen. It looks like a short but I cannot find the source to save my life. I've reset BIOS, run it on a cardboard box, done everything I can think of.

The only remaining thing I could possibly imagine is that the power supply could be failing, but then wouldn't it have other symptoms of this?

ANYBODY have any idea what could be wrong? I can't find anything on this "DMA" failure other than a site telling me it has something to do with controller failure on the board. Still doesn't make sense to me what would cause this but still allow the rest of the board to function normally.

Hello there.

Could you let me know if this is fixed/answered/resolved please.

Thankyou.

JB.