So, I have theater room, where I have my projector hooked up (Optoma HD 70). It has an HDMI input, and I have an XBOX, HD-DVD Player and want to eventually put a Blu-Ray/PS3 out there. I've heard that the length of HDMI cables can cause problems. True? What length do I start having a problem. I'd need to run about 15 feet or so.

I've got a 40 foot running from my receiver to my projector in-wall! I ordered it from Blue Jeans cable. It is really thick and heavy duty - it was so strong that I was able to push it through the wiring conduit built into the room!

No problems with signals then? No delay, etc.?

Under 50 feet you are fine

http://www.hdmi.org/learningcenter/faq.aspx#45

No delays or degradation! See my pictures of my screen shots. There isn't even the "lip sync" issue. BTW, it is Blue Jeans Cables' top of the line cable, see here:

http://www.bluejeanscable.com/store/...eries1hdmi.htm

check out www.monoprice.com

I have a 15ft. 28AWG cable I'm using with that same projector that has performed without any problems, including with 1080p signals. I believe 15ft. is the longest you can practically use with 28AWG, and Monoprice's 1.3a-certified cables don't go any longer than 10ft. at 28AWG. So, if you need longer than 15ft. you need something thicker, but don't worry because Monoprice doesn't sell them too thin.

BTW, you don't need an HDMI 1.3a-certified cable with that projector, but if this is going to be a permanent installation, it might be a good idea to go ahead and get a 1.3a cable. I believe the 1.3a certification is for the extra bandwidth of Deep Color. The HD70 and most other current displays don't support it, but a future display you get might, so it wouldn't hurt to be ready.

My cable is 1.3a and is VERY thick, also wall install-rated. If you look at the picture of my projector against the ceiling, the HDMI cable is almost twice as thick as the power cord!

That covers it about perfectly. I was using a 25 foot run to my LCD for a while. Monoprice won't sell you a cable that isn't the right gauge/length.

That said, the 1.3a certification thing is kind of silly. An HDMI cable is an HDMI cable...the certification just says that it has been tested for 1.3a. But it's pretty unlikely any HDMI cable won't work right with 1.3a.