Does anyone have a distinct "ON" code and a distinct "OFF" code for the 8300HD. I've got a MX-950 that has the same code for on/off. I'm really looking for two separate codes. Thanks in advance for any help.

I don't believe there are any descrete ON/OFF codes for the 8300HD DVR.
I have a MX-950 and a 8300HD too.
I just leave the 8300 on alll of the time.
I have it set to record scheduled programs and don't want it off anyway.

search the setup menu for your 8300. Somewhere in there, you will likely find an option that says something about powering on when number keys are pressed. Set that up, then use a macro that presses a number key, then hits cancel. That way if it's on, you wont change the channel, and if it's not on it will be.

Zmass' answer is the only way to do it. Some boxes have this feature enabled and others don't.

If your cable company uses SARA software the box has the "Power keys: power and numeric" feature, if it uses Passport it won't. If it has this:

Power On:
0
Exit

Note: you may need a several second delay between [0] and [exit] if your box has been idle a while and needs to power up its hard drive, otherwise it may tune channel [0] - which doesn't exist and used to just flash ??? a few times but otherwise do nothing, but on newer firmware versions will tune the next available channel which may be [1] or [2].

Power Off
0
Power

I knew someone would post some workarounds.
But they depend on the cable company using good software.
I have Time warner, and recently they reprogramed all of their boxes with a crapy new navigation system that those work arounds don't work with.
The best I could do was learn the toggle ON/OFF code from the timewarner remote to use when the box has been shut off(everytime they do a damn downgrade, I call it, to their crapy new navigator).
The URC database doesn't have that for the 8300HD.
I just leave the box on myself, and that was why I suggested that to him instead.

If your SA box doesn't have SARA and power/numeric turn on you could always have a timer set in the settings to always power on the box at a certain time of day convenient to your schedule. Of course if this falls before the software update and power off sent by the cable company you'll still need to power on the box manually via the toggle power. Most updates will occur after midnight and before 5 am in my experience. So a timer set to say around 6 am should suffice...or you could just power it up when you've noticed it was off. Remember the good old days when you had to get up from the couch to change channels....what have we become :-)

Thanks tweeterguy.
Unfortunetely I am up all night a lot, and at odd hours watching TV.
So , for me, it's just easier to leave the cable box on all of the time.
Unless TimeWarner turns it off, whom I scream at until I get it back on.
But I learned the toggle ON/OFF from the cable box remote onto a "System power page"(where I have a list of all ON/OFF buttons for all devices).
So when I find the box to be off, I just go into the system power page to turn it back on, since it's too hard to get up and go to box and press the power button.
Yes, I am lazy too.:)

I also leave my Sony DVD mega changer on at all times, since if someone selects a CD/DVD from the CD/DVD menu I have on the remote, the first command sent to the DVD player is a stop command, which if the unit is off, and just been powered on, can cause the DVD player to error. Yes, I could add a delay, but my CD/DVD slection macros have enough delays that it almost takes 20-30 seconds, as is, for a selected DVD/CD to load after being selected, that an initial power on delay would be too much.

But everything else has descrete ON/OFFs, which I use for each activity button, depending on what is wanted.
My listen activities turn off TV, since you are "listening", not "watching" as I tell me wife, whom likes to watch the Music channels, which I have programed on the remote to select on cable box and play through the AVR, but keep/turn TV off for.
I have to replace my Toshiba DLP $300 light bulb at least once/year as it is, so by having the "listen" activities keep/turn the unneeded TV off for, I hopefully save a bit.

I throughly "idiot" tested my remote setup for possible wife factors to make sure nothing can error easily, and found this way to work best.