Helios4 board was designed to either use the on-board LEDs or use an expansion panel (not-available). To use the on-board LEDs insure to switch to ON the dipswitch SW2.
![Dipswitch LED](/img/hardware/dipswitch_led.jpg)
## Reset Button
Helios4 board provides a RESET push button (U16) to hard reset the SoC (System-On-Chip).
We recommend HDD which are designed for NAS (Network Attached Storage). Those NAS HDD are specially conceived for reliable 24/7 operation and offers lower power consumption and dissipation, less vibration and noise, and finally better warranty. We recommend the following models :
**Western Digital** : WD Red NAS (1, 2, 3, 4, 6, 8 and 10TB)
- WD10EFRX
- WD20EFRX
- WD30EFRX
- WD40EFRX
- WD60EFRX
- WD80EFRX
- WD100EFRX
**Seagate** : IronWolf NAS (1, 2, 3, 4, 6, 8 and 10TB)
- ST1000VN002
- ST2000VN004
- ST3000VN007
- ST4000VN008
- ST6000VN0041
- ST8000VN0022
- ST10000VN0004
**HGST** : Deskstar NAS (4, 6 and 8TB)
- 0S04005
- 0S04007
- 0S04012
!!! note
We recommend to order from different shop to avoid having all the drives from the same factory batch. For instance, you should order 2x HDDs from one shop, then the 2 others from another shop.
## HDD / SSD Compability List
Please refer to [Synology DS416j Compatibility List](https://www.synology.com/en-global/compatibility?search_by=products&model=DS416j&category=hdds&p=1) that covers a large number of tested drives. The DS416j used the same SoC family than Helios4.