There is the Password jumper (PSWD), and the CMOS jumper.
The CMOS battery is also termed the RTC battery.
Real Time Clock battery.
The CMOS jumper is labeled as RTCRST.
Real Time Clock ReSeT.
Jumper pin location is confusing if you go with Dell documentation.
Dell Support documentation shows the RTCRST jumper pins near the Intel
chipset, and PSWD jumper pins near the outside edge of the motherboard.
I'm also looking at the Dell Optiplex 330, Technical Guidebook, Inside the Optiplex 330,http://www.dell.com/downloads/global/products/optix/en/optix_330_techspecs.pdf
Location of RTCRST jumper pins, is near the left corner of the Intel chipset, instead of the right as shown above, and PSWD jumper pins are in the same location.
And several views of Optiplex 330 motherboard's on Ebay,http://www.ebay.com/itm/Dell-Optiplex-330-Motherboard-Socket-775-KP561-/140870576837?pt=Motherboards&hash=item20cc8a6ac5
(Nice to have that Zoom in feature on Ebay now)
Jumper pins close to the white SATA 2 connector, are the RTCRST jumper pins.
Jumper pins at the bottom side of the Intel chipset are the PSWD jumper pins.
Jumper cap stays on PSWD jumper pins.
No jumper cap on the RTCRST jumper pins.http://en.community.dell.com/support-forums/desktop/f/3514/p/18683374/18806360.aspx