Is it possible to have two usb dvb-s receivers on the same Laptop?

italights

Standard Member
I am looking to set up an energy efficient htpc, as they are on 24/7. It seems that laptops are 5x more efficient than a pc so I am wondering if it is possible to put 2 usb DVB-S2 receivers into the same laptop and have everything working ok?
 

EndlessWaves

Distinguished Member
Laptops are lower power than most desktops but I'd be surprised if they were that much more efficient, do you have a link to the source of that number?
 

EndlessWaves

Distinguished Member
here are some averages

Approximate Desktop, Notebook, & Netbook Power Usage

seems like 4/5x is about the going rate
That link is closer to 2x for comparable specifications (e.g. ~2.4Ghz Core 2 Duo) and they've clearly not being tested under similar conditions - the desktops are hooked up to much larger screens for example (a 19" screen has 50% more area to be lit than a 15" one).

That's also simply power consumption rather than efficiency, half the power consumption isn't efficient if it's takes three times as long to finish.

A modern low power desktop CPU like the i3-2100T is typically under 50W maximum system load on a minimal system and is frequently used with 90W PSUs like your laptop.
 

italights

Standard Member
So is it possible to run two dvb-s2 recievers on USB? And if not what small i3 setup would allow a pci-e dual card?
 

WheresMyArtisan

Novice Member
Well my HTPC is about five years old, but at the time it was what Aopen called MODT - Mobile on Desktop. In those days there was a big difference in power consumption between the two, so Aopen started building PCs that used laptop components. Mine has a Core Duo laptop processor, laptop-size memory DIMMs and a mobile chipset, but a full-size 3.5" hard disk. It was a very sensible idea at the time.

This was in the days when desktops used a Pentium 4 though - they were horribly power-hungry. This is around the same time as most listed in the document you linked to.

Nowadays there's little or no difference. 450W would be a huge amount of power for an HTPC to use. People tend to over-spec to be on the safe size - a 450W power supply does not consume 450W, but only what is needed.

I'm sure part of the difference is that there's more space in a desktop, so you may as well give the capability. Also there are a number of drive bays and expansion slots, so a PC builder has to leave capacity for someone ramming it full of extra bits.

A laptop does limit its expandability by only having a certain number of USB ports. Each port is limited to just a few watts (the exact number depending on which version of the evolving USB spec you use), so there's a pretty hard limit on what power could be used. Internal laptop peripherals (e.g. wifi, bluetooth) are pretty limited in power due to their size, and many are in fact USB anyway, so follow the same rules.

I currently have 7 USB devices plugged into my laptop. My laptop has 4 USB ports, but the devices are all plugged into a powered hub so they consume almost nothing from the laptop itself.

I'm sure you could run two DVB-S devices on USB. Your only limits would be the number of USB ports, otherwise you'd need to use a powered hub. If you used a hub then you may get issues with capacity if you used several on one hub. In my case, my DVB-T device is in the same hub as my external speakers and my mouse. So the TV signal goes in through the hub to the PC, then the sound goes back out through the same hub to the speakers. It doesn't sound like it should work but it does, perfectly, even when I wiggle the mouse and use other devices on the same hub at the same time. USB is pretty blooming good.

You'd be best to use desktop components but shop very carefully, referring to manufacturers' power specs. Sadly these often aren't easy to find, but hassle them if they don't publish it.
 
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