Wikipedia:Reference desk/Archives/Computing/2012 October 10

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October 10

OS Change– Direct installation

I have Ubuntu 12.04. I want to change to Fedora. The problem is my DVD writer is not working properly. Can I do direct installation (as I have done several upgrades in Ubuntu)? --Tito Dutta ✉ 09:20, 10 October 2012 (UTC)

First, the simple solutions: Turn the ISO file into a bootable flash drive if you have one large enough. Also, the last time I bought a DVD burner it cost $30, and that was years ago.

In order to install without a flash drive or a new DVD drive, the simplest solution is probably to shrink the last partition on your drive. Create a new partition and set it up with the Live installer image. Reconfigure GRUB to let you boot to that. When you boot to and install from that partition, be careful during the repartitioning step of the install so you don't accidentally destroy your install media. After installing, delete the installer partition and grow your last partition to fill the disk.

You could also try installing to a VM, then imaging the OS partition from the VM onto a new partition on your disk, and setting grub to point to that. It would save the step of figuring out how to get a bootable live image onto a partition. 209.131.76.183 (talk) 12:01, 10 October 2012 (UTC)

I'd advice strongly against messing with the grub or partition setup if you have no way of booting your computer if it goes wrong, i.e. if you have no functional DVD-reader. If it is only the DVD-writing that is defective, I'd suggest the really simple solution of asking a buddy to burn the Fedora DVD for you. --NorwegianBlue ^talk 14:47, 10 October 2012 (UTC)

Or spending less than $5 probably on a USB stick, yeah. ¦ Reisio (talk) 17:10, 10 October 2012 (UTC)

iPhone

Being deaf I wonder if there is an app. that will increase the volume of my iPhone. Any ideas will be much appreciated.--85.211.192.197 (talk) 09:57, 10 October 2012 (UTC)

You can get louder results if you hook it up to headphones with batteries and an amplifier, like this one: [1]. StuRat (talk) 10:17, 10 October 2012 (UTC)

Thanks but I'm sorry and I should have made it clear that I was referring to the telephone element of the phone.--85.211.192.197 (talk) 13:50, 10 October 2012 (UTC)

You won't find an app as the volume is built in. I suggest you get yourself this device.--Shantavira|^{feed me} 16:35, 10 October 2012 (UTC)

Ignore secure connection hostname mismatch

I want make firefox ignore https hostname mismatches on some exceptions, is there anyway to do this? 190.60.93.218 (talk) 12:34, 10 October 2012 (UTC)

Lower battery voltage; slower performance?

My Asus Eee Netbook came with a 3-cell 11.1 V battery. I purchased a battery from a reputable eBay seller that is supposedly an official first-party Asus battery compatible with my netbook. The battery arrived in perfect condition and has the proper Asus markings, but beyond that, I am unable to determine if it is indeed an official Asus battery. Anyways, this new battery says it is 10.8 V, 0.3 Volts lower than the original battery.

My netbook runs fine with it and I've been using it on the new battery for a few weeks now. However, I have noticed that it is performing a little slower than before I got the new battery under the same operating environments and workloads. Could the drop in battery voltage be responsible for the drop in computing performance?

Thanks. Acceptable (talk) 20:24, 10 October 2012 (UTC)

I don't think so. This could be the case with analog devices, like dimmer lights and slower fans, but digital devices like a laptop should work at full speed until the voltage drops too low, then they shut down completely. An exception might be if the slower fan speeds cause it to run hot, and it has internal software to choke the processing speed when this happens, to prevent a total shutdown from overheating and/or damage. StuRat (talk) 20:27, 10 October 2012 (UTC)

Did you "notice" a performance change, or did you measure a performance change? We have a list of common computing-performance benchmarks, including a variety of free software implementations. Without direct measurement, it's moot to discuss "apparent" performance. Nimur (talk) 23:17, 10 October 2012 (UTC)

Just use it while it's plugged in, that will show you if the battery makes any difference. And yes, I agree with the above, actually use a benchmark, not just how it "feels".. I personally doubt battery would make a difference, but I don't think it's as inconceivable as StuRat's reply might suggest. Mobile processors use pretty fancy power management these days, I wouldn't be totally surprised if the processor was slowed down as the battery voltage decreased.. Vespine (talk) 04:51, 11 October 2012 (UTC)

While there is a slight possibility, I think it's unlikely. The laptop may vary power usage depending on capacity remaining, it's unlikely to vary it on voltage because there's no reason to. But anyway, the bigger issue is it's very unlikely there's actually any difference in voltage. Unless the battery is different chemistry (which I think is unlikely, they're very likely lithium cobalt oxide cells, perhaps even bog standard 18650 ones), then voltage difference is probably not going to be that significant. It's possible the battery pack charging circuit has a different cut off voltage (4.2V is the general standard but some of the higher capacity 18650 cells by reputable manufacturers like Sanyo allow up to 4.35V IIRC), and of course the discharge curve does vary somewhat from cell to cell particularly between batches and manufacturer (see these random cells [2]), but you generally shouldn't trust the label to tell you anything useful, in particular minor difference in the nominal voltage is more likely to mean the manufacturer chose a different value for whatever reason (most use either 3.6 or 3.7V per cell as was clearly the case for both here). You need the datasheet to tell you anything useful. Incidentally, I think it's unlikely the fan speed will vary much depending on input (i.e. battery) voltage, I'm pretty sure laptops as with desktop PCs use complicated switching power supplies for all components with the variance being minimal and definitely not a simple relation with input voltage. (Remember that over the capacity range of the battery, there is likely to be a 2V variance or more.) Nil Einne (talk) 13:53, 11 October 2012 (UTC)