So at work I have Z620 workstations that run SB-E Xeon 2640s in them. As we all know, these are supposed to have a PCI-E 2.0 root complex and PCI-E 3.0 didn't come until IB-E, or so we thought. While checking lane usage after being curious about 2 Xeons and running 16x to each card (2 CPUs with 40 lanes a piece....makes sense right?) I decided to fire up GPU-Z only to notice both the Quadro K5200 and my Titan X are running PCI-E 3.0.
Sooo I decided to investigate, since as you all know I run a SB-E machine with 3 Titan X cards that definitely need the bandwidth when I run in Tri-SLI*
. It turns out SB-E has the 8GT/s bandwidth but they just never went for certification. This being said, it turns out PCI-E 3 is only locked at the driver level and that can be reversed by a simple hack. The articles I read said that C1 revisions probably won't work, but I ran the hack on mine this morning and it identified as running 3.0. This weekend I'll be doing tests to see if it makes a difference or not with 3 TItans and will post comparisons in this thread.
For anybody wondering why it's a big deal to me personally, is I've been considering jumping platforms to gain the additional bandwidth as it's needed for multiple high end cards. If it works properly it means I can keep my 4 year old setup for even longer while only updating the GPUs saving me money.
I only run one card during the week to reduce heat and the two games I play on a regular basis right now only run on one card anyways. So I keep the other two at work to fold.