Is PCI-e 2.0 really backwards compatible?

UPDATE 1/15/2008: Received my RMA'ed IP35 Pro in the mail the other day from Abit and guess what - it works great. So maybe all my PCI-e spec compliancy ramblings were unwarranted - it was simply a bad pciex1 slot on the motherboard... BUT - according to Abit, they still don't guarantee support for PCI-e 2.0 cards in this board.


Everything I'd read (until now) showed the PCI Express 2.0 specification to be backwards compatible with 1.0/1.0a/1.1.

Interestingly enough, there seem to be quite a few new motherboards in the wild that have problems with the new 8800 GT video cards.

I ran across this after I purchased an Abit IP35 Pro board to use with an EVGA 8800 GT SC. I hooked everything up and as soon as I hit the switch - the thing wouldn't even POST. At first I suspected the 8800 (and I still haven't completely ruled it out) - but after hours of reading forum postings and talking to tech support - I'm leaning toward the problem being a bad motherboard.

For reference, full specs are as follows:
Nspire 650w modular psu
2x1gb OCZ DDR2 Reapers
EVGA 8800 GT SC
Abit IP35 Pro (Bios v14)
WD 320gb SATA

What's so strange about the whole thing is that if I move the 8800 to the second PCI-e slot - the system boots normally. The drawback here is that with this board - running 1 card in the second slot is at 4x instead of 16x. There are TONS of posts on the net - included Abit's own forums - with people having this exact same issue.

Everyone points to the fact that the 8800 GT card is a PCI-e 2.0 card - and the Abit IP35 Pro is 1.0/1.0a. But regardless of this fact - I have seen numerous posts from people with the exact same specs claiming they have no problems with the card and board combo.

Just for the heck of it, I threw the 8800 in an old ASUS 939 (AMD) board I had - and it fired up on the first try no problem. So I'm really having a hard time believing it's the video card.

I really think it's the Abit board. Unfortunately it's been over 30 days now since I originally bought it from newegg - so I have to RMA it directly with Abit. And guess what - they're CLOSED for the holidays?!??!?! UNTIL JANUARY 2ND!?!?! What the crap was I thinking buying an Abit????? Never again.

In Abit's defense - there are many other brands reporting problems. Be sure you do your homework if you're about to buy an 8800 GT.

I've seen forum postings commenting on certain video card manufacturers providing special firmware for the cards to force them into PCI-e 1.0 compatibility mode.. but unfortunately EVGA doesnt seem to be one of them.

I'll update this post after I RMA the Abit board (I plan on cross mailing - so maybe it wont take too long).