As a Comcast Customer, I'm sure I wasn't the only person annoyed by the modem rental increase at the beginning of the year (2011). I never really thought about it before, but I was paying more per year to rent an old DOCSIS 2.0 modem Comcast gave me (which had likely been in countless homes before my own) than I'd spend one time to purchase my own. So, I decided to ditch the rental and own.
At first, I thought I'd just buy what I already had: a Motorola SURFboard SB5120 DOCSIS 2.0. So glad I didn't! Instead I shelled out a bit more money and picked up the Motorola SB6120 SURFboard DOCSIS 3.0.
I read the reviews on Amazon prior to purchase, but was skeptical about the claims of increased speed with this modem. It didn't make sense to me, as I'm paying for an internet package with certain limitations on download/upload speed. It only seemed logical that better technology wouldn't be able to surpass limitations the package I pay for has in place. But in the end, what drove me to choose the SB6120 over the SB5120 was the idea of future-proofing; if I'm paying for it, I might as well get the better option.
Once I had the SB6120 running as my own modem, however, I was pleasantly surprised. My Comcast Internet package deal, which has not changed throughout my recent modem replacement, is as follows: Performance 12 Mbps download/2 Mbps upload with powerboost. Also, my area supports DOCSIS 3.0, so my package, utilizing a DOCSIS 3.0 modem, would automatically increase to 15/3 with powerboost. I took some speed tests (speedtest.net) before and after the new modem, and here's what I got on average:
SB5120 DOCSIS 2.0 Modem:
12 Mbps/2 Mbps
SB6120 DOCSIS 3.0 Modem:
20 Mbps/3 Mbps
Now, is this definitive proof that the SB6120 performs miracles with your internet speed? To many, I'm sure it's debatable. I've read a lot online about how people similar to me (similar internet packages) are getting increased speeds with a DOCSIS 3.0 modem, but there's always someone who quickly dismisses such claims as lies (they typically site powerboost as the cause for such "speed increases").
For me, I don't know. All I can say is that, with my set-up (note: I'm a gamer and run a PS3), I now have a faster internet connection with my new DOCSIS 3.0 modem, which mean the games I play online are blazing fast. Perhaps the old 2.0 was junk, perhaps something else, but the one thing I know for certain is that all I did was update my modem. I'm very satisfied with this purchase.
EDIT: As of 01/22/11, there have been no issues with modem. Have not had to powercycle or reset modem for any reason. Setting up with Comcast was a bit of a pain--was transferred to the wrong department twice, and the directions I received from the technician I spoke with were unclear, but since successfully completing set-up of modem, have had no issues whatsoever.
EDIT: As of 01/31/11: Modem went offline for at least 11 hours after 5 days of uninterrupted connection (occurred on 01/26). Location: Colorado. Recently read 2 other reviews by Comcast customers using this modem in Colorado, and they are not happy. Other than being offline on the 26th for several hours, no other issues to date. Previous modem would also go offline for hours on occasion, so I believe it has to be my connection. Still happy with the equipment. It can work in Colorado.
EDIT: As of 03/12/11: This will be my last update unless the modem malfunctions. Since January 26, 2011, no issues whatsoever to report. I have read that modem may have issues being plugged into a powerstip, and that instead modem should be plugged directly into wall outlet. Modem was actually plugged into wall outlet on the 26th when only issue occurred; since then, have had unit plugged into powerstrip, and again, no issues.
Lastly, read that increase in speed may be due to internet provider's lax perameter's with service during update to DOCSIS 3.0. Apparently, once conversion is complete and Comcast has a better handle on things, download/upload speeds should be more strictly enforced, thus: you get what you pay for and even this unit won't work miracles with speed increases. We'll see.
Note: This modem was selling for $75 new on Amazon back in January. Sorry to see that they've jacked the price up so high, but glad I bought mine when I did.