Mailing List Archive: Off the beaten path question

On Tue, 19 May 2020 16:51:03 -0400, you wrote:

>I am working on a new install of mythtv.? I had to build a new server as
>my old motherboard died, and i lost my
>
>installation.? I have a lot of legacy hardware i'm trying to reuse,
>including quite a few pci cards.? As you might imagine, in 2020, it's
>quite difficult to find a modern motherboard with any amount of pci
>slots.? As a result i'm looking at ways of leveraging the considerable
>amount of old hardware sitting around.? I have a pci expansion chassis
>from the old installation.
>
>Now to my strange questions:
>
>1. What limited amount of horsepower can i get away with using hardware
>encoder pci cards (800i pctv) on a low power pc using a slave backend???
>I have a few old thinclients Neoware Eon/capio/etc sitting around that
>have pci slots, fanless procs, and ide bootable.?? Geode processors.

As long as there is no encoding, the CPU requirements for recording
are very modest. Data is simply copied from the tuners to the disks.

>2.? obviously the main box would have the usb tuner and
>database/transcoding.? Can the main box turn on/off the slave box?
>
>3.? I believe the 0.28 and later versions require QT5.? Are there any
>distributions still being made that boot on 586 code with QT5?? How old
>of a distribution can i get away with and still run 0.31?
>
>Definitely a fringe use case, but i really don't want to throw out a
>pile of old hardware AND buy all new tuners.
>
>The goal would be to not have to put together a fairly power hungry
>slave backend to add to the ones already spinning.? Power usage can get
>expensive here.? My power bill is normally almost 300 already a month
>and it would be great not to add to it.
>
>Any ideas?

Since you have a PCI expansion chassis (an expensive thing these
days), you could consider just attaching that to the new PC via a PCIe
to PCI adapter. That has got to use less electricity than even a low
power PC. There are a number of adapters to choose from. This is the
one that topped Google's list for me and StarTech are a reputable
manufacturer:

https://www.pbtech.co.nz/product/ADPSTT1601014/StarTech-PEX1PCI1-PCI-Express-to-PCI-Adapter-Card

Get a PCIe extender cable so that the PCIe to PCI adapter is on the
shortest possible PCI cable and it should work fine. PCIe is a serial
self-clocking protocol and can be extended for whatever distance you
like using extender cables. PCI cables need to be kept as short as
possible if you want them to work.

I have a PCIe x1 adapter that converts the PCIe bus physically to USB
3 cable and back again at the other end, so that I can have the
adapter under my video card to use the PCIe x1 slot there that would
otherwise be unusable due to the video card's heatsink. I have my
8-tuner DVB-T2 card on the other end of that cable. So one PCIe x1
slot is fine for 8 DVB-T2 tuners, and should also be fine for how ever
many tuners you have in your expansion chassis. Unless the PCIe x1
slot you want to use is also under another card, you could just get a
normal PCIe extender cable which looks like this:

https://www.newegg.com/p/1W7-001G-00003?Description=pcie%20extender&cm_re=pcie_extender-_-9SIA7253CK3419-_-Product

You should be able to find one cheaper than that though - try
Aliexpress if you do not mind waiting for it to arrive. You do need
to be able to get the cables (power and PCIe) out the back of the PC -
I have a slot in my case where the motherboard has no card slot, so I
just run cables out through that.

If you really want to make a difference in how much power your PCs
use, invest in high efficiency power supplies. The 80+ Gold or
Platinum ones. And new hardware these days seems to use less power
than the older hardware and runs several times faster as well. So an
ancient PC taking 230 watts 24/7 can be replaced by a new one that
only takes only 125 watts when running MythTV recording and playing
back. My main MythTV box (Corsair RM650i power supply, 4-5 year old
motherboard) is currently idle and the power supply is reporting this:

root@mypvr:/etc/lirc# OpenCorsairLink --device 0
Dev=0, CorsairLink Device Found: RM650i!

Vendor: CORSAIR
Product: RM650i
Firmware: NA
Temperature 0: 38.90 C
Temperature 1: 31.98 C
Powered: 76760784 (888d. 10h)
Uptime: 217584 (2d. 12h)
Supply Voltage: 230.00 V
Total Watts: 84.00 W
Output 12v:
Voltage 12.16 V
Amps 4.50 A
Watts 52.00 W
Output 5v:
Voltage 4.94 V
Amps 4.75 A
Watts 23.00 W
Output 3.3v:
Voltage 3.31 V
Amps 3.88 A
Watts 13.00 W

So it is only using 84 watts when idle. That is pretty good for a big
PC, and noticeably lower after I switched to a new Nvidia GT1030 video
card a few weeks ago (from a GT220). I had not actually checked the
power use since the switch, and I was surprised to see 84 W. I will
have to see what it takes when busy tonight. It used to be around 150
W.

Our household electricity bill went down noticeably when I last did
major upgrades on my PCs. So running older PCs may well be a false
economy if they are going to cost an extra $100 of electricity a year
to run.
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