[mythtv-users] Motherboard / case suggestions for early 2022 backend

Stephen Worthington stephen_agent at jsw.gen.nz
Sat Dec 11 05:43:44 UTC 2021

On Fri, 10 Dec 2021 20:22:20 -0800, you wrote:

>I'm probably more in the edge case, that I want MB that support 2 video cards - one is for mythtv, and one is for my general linux desktop - I really didn't want to have an extra computer sitting around just to act as a FE, and I do prefer the really snappy performance of using mythfrontend on a fairly powerful computer.
>One thing to look at if you plan to use NVME, is that in some cases, if you use certain NVME slots, certain SATA ports get disabled (you need to look at the MB manual for this).  So you may find a system with 6 SATA ports, but when you toss in a couple NVMEs (for boot drives, database, or other things for performance), you find you are down to 4 SATA ports.

Actually, if you use one NVMe slot, you usually lose two SATA ports,
even if you are not using the second NVMe slot.  That is what happens
with my mother's MythTV box running on an Asus PRIME B450-PLUS
motherboard with an AMD Ryzen 3 3100 CPU.  It is the way the cheaper
AMD chipsets such as B450 work at present.  The upside is that the
NVMe slot is PCIe v3 and very fast.  To get all SATA ports working at
the same time as using the NVMe slots, with AMD CPUs you need to get
the X570 chipset, which is rather more expensive.

I knew about the problem when she bought the motherboard, but of
course I had forgotten again when I had to add another hard drive for
her (from 3 to 4).  She also has a SATA DVD writer, and the new drive
did not work and it took me an hour or so to work out what the problem
was.  Fortunately, I had another PC that was running out of SATA
ports, and had bought two of these:


So I reprogrammed them to use the standard firmware instead of the IBM
RAID version (a somewhat involved process, but instructions are
available out there) and put one in my PC and one in hers.  They
support up to 8 SATA or SAS drives, but with more than 4 running at
one time they run out of PCIe bandwidth if you have the latest SATA
drives that do over 250 Mbytes/s.  There are many different types of
cards like these, with later versions supporting faster PCIe versions
and so more drives on one card at full speed.  But these ones are the
ones that are cheap and available, having been replaced in enterprise
systems with faster versions.  To use SAS controllers with SATA drives
requires that the firmware supports that (it usually does) and then
all you need is SATA cables instead of SAS ones.  They generally do
SATA rather better than cheap SATA only chipsets - they run full speed
and support all the optional SATA features.

So a cheaper motherboard with a card like this is going to be cheaper
than a motherboard able to run all 6 (or even 8) SATA ports at the
same time a the NVMe slots.  You do lose one slot to the SAS
controller card, and the number of slots can be a problem these days
with cheaper motherboards also.  Each slot is much faster (PCIe v3 or
PCIe v4), but there tend to be fewer slots.  So you do need to check
if your tuner cards will have enough slots to go in.  And new
motherboards do not have PCI slots for your old PCI tuner cards.  On
my mother's system, she had two Hauppauge TD-500 DVB-T PCI cards, so I
got her a PCIe to two PCI slot converter.  It plugs into a PCIe x1
slot and the two dual tuner cards work just fine sitting in the PCI
slots out the back of her MythTV box with the cable going inside to
the PCIe slot.

More information about the mythtv-users mailing list