Hi, been ayway from the quiet pc building for years. Planning to get a new computer and want alot of hard drives.
Is't madness to event try it or is't possible ?
How many Watts do you need for a build like this ?

(i assume op wants "eight" HDD's.)
of course its doable, and it wont take that much power, depending on other components....but the real question is why?
what else is this rig going to be doing besides running 8 HDD's?

and, unless youre going to suspend 8 drives, it wont be silent....

It's possible, but you still won't get silence from any multi-hard drive system. I had eight WD Green drives in my server a while back, and it was definitely quiet once I suspended the drives (a necessity IMO) but still audible if you listened for it.

viewtopic.php?t=49709

I'm not aware of a case with room to suspend 8 HDDs.

Imho a system with 8 mechanical drives can only be quiet if placed next room.

ops sorry for the typo

Was thinking about a Fractal Design Define R4 case, it have some rubber gromit for the hard drives. Wont that help ?
Need to upgrade my old computer and then i need space for my movie collection, so i thought a new computer with alot of space would be a good idea.

With NoVibes III HDD Decoupling Rack and enough 5.25" bays you can decouple eight drives.
The questions remain, why?
How much hard drive space do you really need and does it have to be in the same computer as your work machine?
Eight 5K drives might not be silent, but tolerable if decoupled and you don't have to access all at once.

A NAS for 5-8 drives cost alot, and i need a new computer. So why dont get a new computer with alot of space ?

First, here's spcr. You won't get any advice without reference to noise.

Second, you're always talking about 8 drives. How much TB do you really need? If you're talking max data you're in for 8 x 3TB or even 8 x 4TB. You really need 24TB of storage? Then you should probably talk to Kim Dotcom and ask for advice

hehe yeah maybe an idea Right now I need like ~7-8TB storage but it would be nice to have space so I can add another drive or two in the future.

Something like 12-14 dB if thats possible

Amazing how often this topic comes up... when we ran a whole series of home server build guides that's linked to the main menu!

Look on the main left column on any SPCR main site page, and you will see "Silent PC Build Guides"
Start here -- Silent Home Server Build Guide -- and you will get to Mid-Tower Home Server Configurations. That and the next 4 pages or so detail pretty much everything you need to know about building a multi-HDD silent home server. We got our 9-drive (WD GReens) config to 18~19 dBA @ 1m. 12-14 dBA is unreachable at this time except perhaps in a totally custom-built concrete case.

thanks MikeC, I did some re-thinking after reading the answers. Still gonna build a big storage computer, but I gonna place it in a diffrent room.

Use the silencing techniques suggested anyway -- I remember visiting a friend whose server 2 floors away could beheard constantly!

Will do that.

How about this:

Fractal Design Define R4
Corsair XMS3 DDR3 PC10666/1333MHz CL9 2x4GB (CMX8GX3M2A1333C9)
Intel® Core™ i5-3475S Processor
Asus P8Z77-V Deluxe (Fan Xpert 2)
Seasonic X-560 560W
Fractal Design Silent Series R2 140mm (X 3)
Prolimatech Megahalems
Intel 320 Series 2.5" SSD 120GB
Western Digital Caviar Green WD20EARX 64MB 2TB (X 4)

What do I need to change ?

You don't need 3 more fans. I doubt you need any more case fans than the 2 the Fractal case comes with. Check out those build guides linked earlier -- more closely, perhaps -- and see what we did for cooling in a hotter system than yours with 9 drives.