Specs: Win7 64bit SP1 / Intel i5-3750 / 8GB RAM / ASRock B75M R2.0 MoBo / ADSL-2+ via ethernet
Router: D-Link Model # DSL-2642B [specs &c - http://www.dlink.com.au/products/?pid=dsl-2642B ]
The day-to-day speed is pretty damn good for Sydney suburbs really. Actual download speeds from, say, Google or Microsoft, gets to around 1.8Mbps or a bit more. For regular usage, maybe 1.0Mbps average (obviously varies greatly).
So, why am I here? I did a speedtest (cnet.com.au) which rates "your line speed" at over 12Mbps (~same result when repeated a few times). The thing is: the D-link router has a specified maximum download speed of 8Mbps.
I realise this is a little unlikely, but my question is this: if I was to get a new router with a max d/load speed above 12Mbps, would that (alleged) extra available 4Mbps of line speed result in an *actual* increase in my internet speed???
The secondary info with respect to the above query relates to the fact that the D-Link router is a few years old and it's still in good working order. If I upgrade, it will be a good router to keep as an emergency backup. I'm also thinking of getting a dual band router for future proofing in one sense, but also because there are mobile devices here, or that visit here regularly, that have access to the 5GHz part of the spectrum.
What makes you think that your current router/modem combo is limited to 8 Mbps?
I ask for two reasons.
The first is that according to the data sheet for the router/modem combo that I got from the link you provided, it would be capable of either 8 Mbps, 1.5 Mbps, 12 Mbps, or 24 Mbps downstream…depending on what DSL connection is used (i.e. G.dmt, G.lite, ADSL2, and ASDL2+ respectively). Now, as I understand DSL (and my understanding of the deep technical info is limited), it is not just as simple as which connection type you use…as I understand it, your distance from the exchange will also impact whether G.dmt (aka ADSL1) or ADSL2 actually gets you a better download throughput (aka "speed").
So, it would appear that your current modem can be setup to different modes that in theory (barring other potential factors) would allow you to use ADSL2 or ADSL2+ "speeds".
The other reason is that your speedtest result was 12 Mbps. Based upon my trying the CNET.com.au test (to see how it presents the information), that would suggest that you are ALREADY getting 12 Mbps, which if your router/modem was limited to 8 Mbps would be impossible. In other words, your speedtest results tends to suggest that you are not limited to 8 Mbps.
Now, just a general note about so-called "speedtests" in case you were not already aware. It is important to keep in mind that a "speedtest" is strictly testing the "speed" (technically is it throughput) between your computer and the speedtest's server. You will can get different results when testing with different servers. For example, when I use www.speedtest.net (it allows you to pick different test servers around the world), if I pick a Sydney, AU server I get about 25 Mbps, but if I pick a Comcast server in Chicago (I have Comcast), then I get about 35 Mbps. Those different "speeds" are a function of the different "paths" between me and each respective server…and it is not just a function of physical distance (I believe that tends to impact pings more than throughput).
This then leads to the issue of actual use. While remembering that different speedtest servers can give you different results, that same effect and others translate into "real usage" (rather than just speedtests). Just like a speedtest with different servers, going to different websites will result in different paths taken on the Internet. Think of it like driving on the road. You might have a hundred different ways that you drive from your home to work. Each way will have different physical distances travelled, but also different speed limits and different levels of traffic congestion. Same basic type principle applies to the Internet. So, different paths may have different levels of traffic. Then there is the web server you are connecting to at the end of the path. It can have different levels of use depending on which site you visit as well as having more "powerful" servers (i.e. a site like CNET can likely handle more connections than some personal website that some person runs off their home computer).
All this explains why you get around 1 to 2 Mbps when doing "real usage" while getting 12 Mbps with a test server.
I apologize if you already knew all that.
The overall result is that based upon the information you provided, it seems to me that you likely will not improve your day to day speeds with a new router/modem, but I could be wrong.
Now, a new router/modem might be worth it if you want/need better WiFi. Keep in mind, however, that any Internet connection over WiFi is essentially bottlenecked by your DSL Internet speed. So, in that sense, going to 802.11n or even 802.11ac will do very little for you. Where it can potentially help is in signal distance (802.11n has better range than 802.11g) and interference if you get a dual band router (the 5 GHz range tends to have less interference than the 2.4 GHz range, but does also tend to have a small signal distance). Both of those can indirectly to better "speeds" for WiFi devices (i.e. WiFi "speed" will be function of distance, so since a 802.11n network has better range, it can likely get better speeds at a specific distance than a 802.11g network). The only other possible benefit is if you need to transfer files on your local network between computers where at least one is a WiFi computer…then an 802.11n network's greater "speed" can be of potential benefit.