The 1720dn doesn't match its claimed print speed when printing multi-page documents. Dell claims speeds of up to 28ppm but our five-page text document took 34 seconds to complete, which converts to a print speed of 8.8ppm. Unusually, this appears not to be a speed restriction in the print engine, but slow data transfer.
Using the same USB2.0 connection we use for all printer tests, there is a noticeable pause between pages as if the printer's processor is waiting to receive data. This theory is backed up by the five-page text and graphics test, which prints the same page image five times and therefore requires just one transfer to the printer. This document completed in 21 seconds without faltering, giving a speed of 14.3ppm. This is considerably faster than the text document, but still only half the rated speed.
The quality of the printed pages is very good. There's no noticeable spatter and the crisp, black text is very readable right down to small character sizes. Greyscale output is also good at the default 600dpi resolution, which is boosted by resolution enhancement to an effective 1,200dpi. Different shades of grey are easily distinguishable and despite some noticeable dither, text on top of grey shades is clear and readable.
We printed our test photo at both the printer's effective 1,200dpi and also in a mode where it prints at half speed but with full 1,200dpi resolution. The true 1,200dpi print is smoother than the simulated high-resolution one and there's less banding. However, both are acceptable as laser prints.
You can buy toner for the 1720dn in 3,000 page or 6,000 page capacities and the photoconductor drum is designed to last for 30,000 pages. The 6,000 page toner cartridge represents much better value and using this, we calculate a cost per page of 1.53p – reasonable for a printer at this price point.
Dell’s 1720dn is cheaper than its Lexmark rival and also less expensive to run. The only thing you can level against it, given its useful feature set, is a hesitancy when printing long documents, which seems to be down to a less capable processor rather than a slower print engine. A good printer for the home office or small business, particularly if you're already a Dell customer.