klor

Optional means flashable, so user can flash missing BIOS anytime later?

Yes, these are common symptoms for external USB devices, so I can imagine this for some raid cards, too. Thank you for for the detailed explanation, I learned a lot again. Thanks! So I go with LSI 9211-8i using IT mode. Can I boot up from disks connected to LSI 9211-8i? Are the disks shown in the BIOS, UEFI or appears just within the card settings? (I know Unraid boots from flash drive, but I need universal hw configuration, which can be used for multiple purposes, if needed later)

So I should go with LSI 9211-8i in IT mode. Just one thing I remember, that my Areca raid card had the option to set pass through mode for each drive attached. So the OS has direct access to the drive attached to Areca raid card with pass through mode. Likely I will stick with LSI 9211-8i, but still curious if the pass through mode in Areca cards are something similar like IT mode in LSI.

Why the raid controllers are not recommended? They conflict with Unraid?

Anybody has experience with NEC N8103-150 (LSI 9271-8i) RAID card? Available on Ebay: https://www.ebay.com/itm/384844864669 Price seems to be good for $35. Product info is available from here: https://www.58support.nec.co.jp/global/download/pdf/NECRAIDControllerR1.0.pdf Should I try this one? Not sure, if I should go with NEC one or wait for an original LSI one.

Motherboard has more free fan connectors. But the tower case has no place to screw another fan onto the side of the case, which could blow air to the cards from top direction. I'm thinking on top cooling fan like this: Vertical heat dissipation of North South Bridge, Support 12cm 14cm cooling fan: https://a.aliexpress.com/_mtUjYPK This might be placed over the LSI card to provide further cooling.

How do you detect overheating of an LSI card? Is there thermometer sensor implemented, which can be read by drivers or firmware?

I use Thermaltake Armor tower case. It does not seem to be possible to attach side fan: https://www.newegg.com/amp/black-thermaltake-armor-series-atx-full-tower/p/N82E16811133154

I did read, that LSI cards are getting very hot and needs additional cooling, because the attached factory heatsink is not enough. What is the experience? Does it cause problems, if only the original heatsink is used?

Which is the cheapest card you still recommend, with at least 8 SATA ports?

I understand now. Thanks!

I understand. So SATA multiplier affects performance, when parity checks and disk rebuilds are done.Thanks! I'm thinking, if my mentioned cards are using SATA multiplier or not. PCI-E 4X 10 Port SATA Card with PCIE3.0 (using ASM1166+JMB585 chipset): https://a.aliexpress.com/_mOKtbzq ASM1166 chipset supports 6 SATA disks: https://www.asmedia.com.tw/product/45aYq54sP8Qh7WH8/58dYQ8bxZ4UR9wG5 JMB585 chipset supports 5 SATA disks: https://www.jmicron.com/products/list/15 So I suppose this card supports natively 10 SATA ports without multiplier. Am I right?

I use traditional SATA drives.

I still don't get why the port multiplier should be avoided.

Yes, but I plan to hang all disks on the same card. Should work all disks, or nothing. Just imagine the situation, that 6 disk are attached to the SATA xard, 2 to the motherboard SATA. If the card is broken, then suddenly 6 disks will be missing, 2 will be still available, which will result unwanted situation.