Battery Life

Possibly, but i would only venture 10-15 more min... So, if battery life is your concern, get the parts you REALLY want, and then get a second battery..

I'm a very battery-life consious user also, I just ordered a 5680 for school and was thinking along the same lines you were. I decided to get the P4 3Ghz and 60gb 5400rpm drive AND a second battery. I originally thought the 5400 rpmwould be a nice compromise of speed and power saving (coz it spins slower for less battery usage, but has 16mb cache which would help some), but come to find out if you wanted to spend the money, the 7200 rpm drive gives you around the same life as the 5400 rpm, or so I've read in other posts. My advice is to get the parts you want and the second battery, from other posts I've read people get very long life off of two batteries, if you properly cycle them every now and then. All depends what you're doing of course ... word processing with the screen brightness turned down shouldn't suck too much juice.

Does enabling HT cause more battery power usage? Or I should say, will I get longer battery usage time if I disable HT in the BIOS. If so, by how much? Anybody have any specific experience?

I am pretty sure i read somewhere here that it will. If you think about it HT basically tells the computer there are two processors (not that i have any clue how one processor could even be confused for two because it is no where twice the speed) but it would make since that it uses a little more battery life. I have never actually tried it and am too busy to try it now. you should just give it a shot if you have a few hours. Just make sure the drain on your cpu is the same when you test with and without HT. To spam this message, does anyone know what HT is supposed to do because i see very very very very very little increase in speed between the two (enabled and disabled). Thanks

I believe the over all effect of the HT is that two different programs can run at the same time pretty fluidly. Of course without HT you get the apparancy that many programs are running at the same time, but really they are each taking really fast turns.

I have noticed being able to do 2 things at once with seemingly better performance, such as keeping a 3d animation running in one window and compiling an application in another.

Now, perhaps someone else can give a better and possibly more accurate explanation, because a lot this "technology" is a whole of marketing talk. Like "centrino", give me a break.

if you search, somone posted a link to an article which explains ht in depth very well. i believe it was in the off topic section. i'm just too lazy to go find it myself right now.

you know, I would like to search on ht, but the system won't let you search on two letter words and if I search on ht* I get hits on everything like "http://www.sagernotebook.com/support" and "bright"

k sera, sera

Intel's web site has some good explainations of HT.
Whilst there is a lot of hype surrounding it, HT does give certain programs a kick along. Depending upon the type of applications running you may or may not see an improvement.

Most windows programs are HT blind in that they only work with one CPU. Adobe Premier Pro (not the older non-Pro version) is HT enabled which means that it knows to split its tasks into two to make use of the HT feature.

As to what it actually does: the P4 CPU has several different execution units (branch predictors, ALU, FPU, bus engine etc) which are normally in lock-step with each other. If one instruction stream is currently using some of the execution units then others might be idle. HT removes this lock-step restriction and allows different execution units to accept instructions and/or data whilst the other execution units are busy. The P4 has enough execution units to effectively appear as two CPU's. In theory a P4+ (not a real CPU) might include more execution units and could theoretically appear as 3 or more CPU's. The number of virtual CPU's is a function of how many idle execution units the CPU might have lying around for any given program (more correctly execution thread).

Unix systems and software are a bit more adept at handling multiple CPU's. Sun's Solaris for example does SMT and SMP. Unix processes can also make use of what is called multi-threading. Multi-threading is enabled by a programmer when they want to have the program do two or more things simultaneously.

Windows programmers have only just begun to develop multi-threaded programs (older Win9x did not have efficient multi-threading support).

Conclusion: HT under Linux works really well. HT with XP works well but most existing Windows apps are not written to take advantage of it. Newer Windows apps will start to use it as programmers insert threading into their code.

As to battery life I doubt you would see any difference between HT and non-HT. There is a minor power difference because you are working more bits of silcon more often but relative to the overall power of the CPU, LCD backlight, GPU, memory and disk drives it will not make much difference. To extend battery life look more towards slowing the CPU down (option in BIOS), turn off disks and LCD backlight earlier when idle (Win XP power options). Memory and GPU will use less power if they are used less.

HT

Most of modern games are multithreaded, so they should theoretically benefit from HT too. (In fact games are only mainstream multithreded applications on PC that I can recall)

Well, the OS is multithreaded, or you wouldn't be able to run but one program at a time.

Many programs are multithreaded, not just games. They use timeslicing, each thread within the system gets to execute for a given time when it needs execution, then focus moves to another thread. There is where priorities come in. NT systems have 6 priorities, normal, above and below normal, low or idle, high, and realtime. Realtime is exclusive operation. The reason the computer appears to freeze in realtime operation is because one or more threads are set to exclusive operation, which may rely on the OS to draw graphics or perform RPC calls, but can't execute, so it will wait indefintely (freeze) for something that will never happen.

Multithreading has been around for a LONG time, not just in *nix and Windows. It exists in the first versions of DOS to a degree.

I would have to disagree with DOS being multi threaded. What may cause confusion is that multi-threading is different to multi-tasking. Multi-threading is a more recent addition to the programming environment. Multi-tasking has been around since the early days (1960's) of computing.

Multi-tasking is where multiple programs each get a slice of time to run. The OS then performs interrupt on the program saving all of its state (thus suspending it) and then restores the state of a different program (thus running it). This is sometimes called heavy-weight task switching or processes. Most operating systems (at the time) ran as monolithic kernels that could service no more than one interrupt (task switch, disk i/o, input etc) at a time (albiet very quickly).

Multi-threading is different. It requires both library support and operating system support. Multi-threading is where one program can have several "trains of thought" if you like, whilst still being one program. Sort of like working on several parts of the problem all at once. Threads are sometimes called light-weight processes. They can be started and suspended much quicker because less information needs to be saved/restored (they all reside inside one process or program).

To be really useful though threads need a multi-threaded kernel. This is a kernel that itself is made up of lots of small threads and can do multiple things at once whilst running *inside* the kernel. These are sometimes called micro-kernels (Mach from Carnegie Mellon Uni being one of the first). When David Butler (the chief architect of DEC's famous VMS operating system) jumped ship to join M$ he created NT using the concepts in Mach and VMS. Mach went on to form the underpinings of OSF (Open Systems Foundation Unix) and later IBM's AIX and DEC's Tru64 Unix.

Sun on the other hand developed their own version of multi-threading called Solaris 2 (the old SunOS or Solaris 1 was a monolithic Unix kernel as was Linux). Solaris was the first true multi-threaded multi-tasking OS that supported SMP.

Since XP is based on NT it too is multi-threaded and can make use of both SMT (ie. HT) and SMP (ie. Dual Xeon CPU's). XP is a multi-threaded and multi-tasking OS.

Programs may be multi-threaded if and only if the programmer uses the constructs provided by the libraries and OS (these are sometimes called POSIX threads - Sun of course had its own version of threads). If a program is written as multi-threaded then if the OS can support it, the OS will allocate individual threads to individual CPU's (either virtual like HT or real like Xeon's).

Bottom line most older (> 1 year) PC programs are not multi-threaded, some newer programs can be (if the programmer has designed the program to take advantage of multi-threading).

To stay on Topic ahem gentelemn

a Pentium 2.8Ghz system with a single stick of 512MB 400Mhz
4200RPM Hardrive

will offer at best 17 minutes compared to a

3.2Ghz system with a 2 sticks of 512MB 400MHZ and 7200RPM hardrive

If you want battery life find somethign without a Pentium4 in it


Celeron, Pentium M, Athlon XPm, Pentium4m are great alternatives and you will have a 60-110% performance gap compared a pentium4 desktop based system