There is no 6 pin 150W power connection because the power supply is LESS THAN 300W.

The 9020 mini tower DOES NOT USE a standard power supply.

http://www.moddiy.com/products/Dell-OptiPlex-9020-PSU-Main-Power-24%252dPin-to-8%252dPin-Adapter-Cable-%2830cm%29.html

Mini tower can use standard power supply WITH AN ADAPTER.

EVGA NEX 750B for example.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817438007

Is there any 500 W for dell 9020?

I want a cheaper PSU.

Is that Cooler Master eXtreme Power Plus 550W ok for dell 9020?

I mean the size and power configuration.

Thanks

No power supply from anyone other than the stock Dell works without the MODDIY adapter.  Only the Tower version can take a standard 80 percent efficient EPS12v power supply.

Can I use  Cooler Master eXtreme Power Plus 550W with moddiy adapter on DELL 9020? Thanks

No because the RS-550-PCAR-E3  is an ATX 2.3 power supply not an EPS12V haswell certified power supply.  Its not EPS 12V   80 percent efficient.  This model has not been manufactured since 2012.  4 year old insufficient power supplies are likely to blow up your motherboard and fry everything.

http://www.coolermaster.com/powersupply/extreme/extreme-power-plus-550w/

You appear to be choosing based on WATTS and price rather than actual SPEC and Current output.  There is a reason why one unit may be $29 and another with the same WATTS is $99 or more.

Any other suggested PSU that can be used?

I want a cheaper one.

Please help me. Thanks a lot.

Cheaper one will not work and will damage components and fry everything.  

EVGA SuperNOVA 750 B1 110-B1-0750-VR

http://www.newegg.com/Product/Product.aspx?Item=N82E16817438025

Also, is that Corsair CX500 V3 (www.price.com.hk/product.php ok for dell 9020?

Is that this one www.price.com.hk/product.php

If I install it in dell 9020, is that 100% so that the computer will work, and not blow up the MB?

Thanks for you help.

CX500 is not acceptable.

Yes that's the one.  Doesnt work in a 9020 however without the MODDIY Adapter.

Why 500 W is not capable for 9020?

Is that www.price.com.hk/product.php EVGA with adapter will 100 % work on 9020 without burn the MB?

Is that EVga supernova 750 b2 or g2 suitable for 9020?