Adding a WD 1TB Green Drive...
 

I currently have 3 HDs, this will be 4th, will be used sticky for backup. I know where to the plug the SATA cable but I was wondering if I need to run a new cable from the modular PS for the 4th HD? The existing cable has three adapters/plugs from the one line. Can I split off one of the three or should I run a new line from the PS? TIA!

You can split off. I have 8 HDDs running off a single "line" without any apparent issues.

If I had the choice I'd run another line from the PSU because I find adaptors can get loose more easily than cables clipped to my PSU, but as JD said it should be fine. (my PSU has a modular cable with 4 SATA, and I used that with no issue with 3 hard drives and an SSD)

I'd like to see a combination of 4 hard drives that can draw anywhere near 240W :thumb:

**Everything You Need to Know About Power Supplies | Hardware Secrets

Hard drives use the most power upon initial boot and then almost nothing after that. Its why some RAID cards allow for staggered startup so that not all the drives are powered up at once and doesn't cause as much strain on a power supply.

But 4 drives on one string is harmless.

Thanks gentlemen, I appreciate the quick feedback. Cheers!

I merely clip more SATA power plugs onto the cables ;) They just push on so it's quite simple. Helps cable management too when they're all lined up properly. Obviously a slightly more "advanced" approach though.