There are at least three bands with this name:

1) suffix is/was a screamo band from Chicago. The band members have started new projects Ittō , Coping, and lord snow

http://suffixchicago.com
or
http://www.myspace.com/suffixchicago

2) SuffiX is a hard-rock / metal band, originating from Leiden, The Netherlands.

The band SuffiX is an energetic five man metal formation, from Leiden, The Netherlands. Founded in 2004 and having changed members several times, the formation now consists of Paul Dekker (vocals), Joris Scharpff (lead guitar), Sjoerd van der Vlugt (rhythm guitar), Rustin Ramadhin (bass) and Robin van Leeuwen (drums).

In September 2011, SuffiX has released their debut album named 'Your Turn'. The album is composed of 11 tracks (not including extra's), totaling one hour of melodic but heavy riffage. The single 'Painkiller' is indeed a prime example of their style: the combination of grunts, deep bass and aggressive guitar lines easily flows into the more cheerful chorus, followed by a well-fitting solo and instrumental section. Your Turn also shows clearly that SuffiX is also capable of other styles, as 'Deny All Gravity' and 'When Destiny's Fallen' both demonstrate.

3) SuffiX is a metal band from Stockholm, Sweden. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.