I need advice about purchasing Optiplex SFF desktop

I need to purchase desktop computer(s) and it must be in small form factor.

I am considering Optiplex 3020, 7020 and 9020. Processor should be Intel I5 +

Now, computer noise is extremely important factor (of course the lower the better).

I have looked at technical guidebooks:

For 3020:

http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/CSG-EN-XX-ALL-OptiPlex-3020-with-micro-Technical-Guidebook.pdf

For 7020:

http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/CSG-EN-XX-ALL-OptiPlex-7020-Technical-Guidebook.pdf

and for 9020:

http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/CSG-EN-XX-ALL-OptiPlex-9020-with-micro-Technical-Guidebook.pdf

for noise data.

A-Weighted Sound Pressure Level at idle is (for similar processors 84W) at load nose rise proportionally for all models

3020: 20.6dB idle, CPU Stressed 33.8dB

7020: 29.7dB idle, CPU Stressed 41.1dB

9020: 18.0dB idle, CPU Stressed 30.9dB

However levels for 7020 are measured with graphic card, and there are no data for computer without graphic card.

7020 is somewhat best choice but I am concerned about noise level (it is really of absolute importance that computers are as quiet as possible)

Can I assume that noise increase is (from 18-20 dB for 3020 and 9020 to 30dB for 7020) is due to graphic card.

Thank you for any answer,

Regards.