90W power switcheroo for quad core T520 - is this possible?

[hman]

Way too much thought is going into this computer purchase, but I'm almost done.

After even more reading, I believe the T520 is the choice. Now, the decision is between
dual core i5-2540M, dual core i7-2620M, or quad core i7-2720QM CPU.

I had completely decided on the dual core, because Lenovo will only sell the
larger/heavy 135W power brick with a quad core CPU, and discrete graphics on the T520. That's
basically a show-stopper for me - I don't want to lug that heavy brick on travel.

I contacted Lenovo, and was told that the quad core T520 will run off the 90W power
supply (your mileage may vary - but that's what I was clearly told - twice).

If that's the case, why can't I do this - since I want a dock, buy the Mini Dock that comes with a 90W
power supply. Since Lenovo forces the 135W power supply on us when buying the
T520 quad core + discrete graphics, why can't we swap the 135W power brick and connect it to the dock,
and use the 90W power supply sold with the dock to run the T520 when traveling? This appears to solve the "problem".

As I understand, the quad core CPU is only 10W higher maximum power compared to
the dual core (45W vs. 35W). Since the adapter plugs are the same for the 90W and 135W supplies and docks,
and the literature says that the docks sold with the 90W or 135W power supplies are
exactly the same, why can't this be done? The Lenovo rep said that this "can't" be done,
even though he said that 90W would run the T520 with quad core CPU. Doesn't make sense.

Hopefully will complete the decision tomorrow (with your help)

Hman

[amb00]

Don't remember exactly, but I think I read somewhere that the _laptop_ is not letting you, even if in theory, 90 watts could be enough.

BTW why a quad-core ? I don't think the time has come for quad-cores on laptops.. they consume too much and they won't be fully utilised by applications.

[hman]

Good question, amb00. It would be easiest for me to just go for the dual core CPU.
That might actually be the best solution for the next year or so. I'm thinking though
that in a couple of years, programs will take greater advantage of the quad core,
and I tend to keep machines for a while.

I've been reading a lot about advantages of dual vs. quad core, and at the moment,
there's no clear and easy decision between the two. The thought of going with the
quad is more future-proofing than anything else.

Consider this as well - the quad core CPU is only ~ $35 more than the dual core! That
CPU also gets excellent benchmark scores. And, I don't expect it to draw too much more
power. At maximum, it's only 10W more power that the dual core (45W vs. 35W).

Actually, if it weren't for this 135W power brick "issue", I think it's a very good choice.

I'm thinking though that with the relatively "high maintenance" antivirus program that
my business uses + Windows 7 + applications - even if the applications can only
take advantage of single CPU, there are still plenty of jobs that the OS can offload
to the other CPUs.

Anyone want to weigh in opinion about dual vs. quad core for laptop use? Perhaps
the 4 threads of the dual core CPU will be more than enough for business use and
some scientific calculations? The high performance computations that I need are
mostly all done by Linux servers.

Going with the dual core of course would make this power supply switch unnecessary.

[amb00]

If windows is smart enough to utilize al cores then yes, the many the better for different programs (each running on one core).
But except new games, most applications aren't really designed with parallelism in mind. Parallel doesn't just mean gui on one thread and the logic on the other, like most programs are beginning to be created (finally); it's also the algorithms. And doing this takes time which companies don't have. Until frameworks integrate better parallel programming I don't think that many cores will help if they consume much.
Now there is the other side when you use A LOT of programs at once AND windows is smart enough to handle them on separate cores but in a smart way, depending on the needs of the programs. Yes, I don't really trust MS to spend a lot of time on this. Eye candy is the new thing so they try to make windows prettier. Modifying the existing code base of the OS is not an easy task and requires money above all

The good news about .net is that MS is trying to make parallel and distributed programming easier so in the future, programs for windows might be "better".
Sadly, Java lags behind on the easy part with creating parallel programs.

That's my opinion, as a computer engineer.

BTW I opted for intel P and not T processors on my thinkpad, because P consumes less and the extra speed the T9400 gives is not that substantial (even with increased cache).

[Q-Ball]

W520, with the i7-2720QM, is 20 bucks more than the T520, with the i5-2520M. Except for the graphics card both configurations are the same.

T520 with quad-core, or anything more than the i5-2520M is a total waste of cash. There's no way around that.

Go buy the more powerful W520. It's quad-core, and it's got a real graphics card rather than the bottom-line 4200M.

It doesn't seem logical that you're worried about the weight of the brick when you'll be toting the battery slice around. That's way more weight than even the 135W brick will give you.

You know what else doesn't seem logical? If you're worried about weight, why are you buying a ThinkPad? If you're new to this, you should probably know that ThinkPads are one of the heaviest computers you can buy, due to their construction. So if you're worried about a few ounces and a few square inches of space why are you buying the HEAVIEST computer out there?

So you know what?
GO BUY A CASE.
That way, you'll be able to carry it no matter how much or how big it is.
Besides, as I mentioned before, YOU'RE NOT GOING TO EVEN RUN OUT OF BATTERY LIFE since you're going to get 6 + 6 HOURS of reasonable use, even with the Quadro 1000M ON, since you have the slice.


That's all.

[hman]

Wow - sorry. I didn't mean to get you upset. The decision isn't as easy as you say. Our needs are
all different.

The battery slice is not to be carried around in a case all the time. It will be used for very long times off power
either at meetings, or at home.

For travel, I want to carry a 90W brick, max. The ultraslim brick is especially nice. The W520 will only
work with the 170W brick (and I don't want to pull that whopper out at a meeting), but a quad
core T520 will work with a 90W brick. So, even if I have to give up the 4 DIMM slots, and
the USB 3.0, that's the choice.

So, I think there's a solution - have the T520 quad core, as I don't need the highest end graphics.
Seems pretty logical, but took a while to decide. I do appreciate your help with that.

I hear what you are saying re: the W520 being a very good deal pricewise. I agree. T520 and W520
are really so close. Some people will key on the 4 DIMMS, USB 3.0, and cranking graphics. Others
will key on the small brick. Maybe there are some others out there that might agree with me, and
so I hope this power brick swap idea helps them. It will really help me (if it works as planned).

Again, sorry - I didn't mean to get anyone hot and bothered. No more talking about this.

p.s. My present Thinkpad is the same weight as the T520, so I know the weight. I've used it as a
desktop replacement for 6 years - it has given high performance in the dock, and the hi-res screen
that I want when traveling. And, IBM/Lenovo have the best Trackpoint of any machine - which I find a
total must. So, summing up those three points is why I'm carrying the "heaviest" computer out there (Actually,
you know that it's not the heaviest - the 7xx series Thinkpads are heavier, as are some Dells that I see
some colleagues using And the T520 with ultraslim 90W brick will be lighter than the W520 with 170W brick.
But, I'm not going to debate the difference - we could carry either variant, it's just a choice.

p.p.s. Also - not all planes have plugs, and it's not always easy (yet) to plug in at airports, and my last trip
took me 26 hours door to door (crazy, I know, but it happens). Unsure if I would want to tote the battery slice on such a trip, but it's always an option. Such a trip might happen again this year.

p.p.p.s. Actually - Battery slice is listed as 1.35 lbs, 170W power brick is 1.70 lbs, so literally, it's inaccurate to say that
the battery slice is heavier. Difference is small though.

[Q-Ball]

Sorry... I'd just received some, uh, 'unpleasant' news.

That's interesting, though.
I'll test the 90W brick when my W520 arrives and get back to you since it's the same configuration as the cheapest W520 (don't know if anyone's tried it with a Quadro 1000M which has lower power requirements than the 2000M does) and I'll also have a 90W supply on hand, but its arrival date is too far off.
I'll be able to figure out what happens when you use it on a notebook that requires a hair over 90W to run since most tests I've seen have it pegged using 105 or 115 watt configurations.

You can also just switch to the Intel graphics if you know that you're going to be without power for a long time but I can attest that you'll have at least 4 hours of working time (that is, taking notes and presenting) with a W520. Since that shuts off the draw of the 1000M you can be working for quite some time. That may be your best option even with a T520+quad-core.

How long is a long meeting for you- i.e. when would you consider using the battery slice? 4 hours? 8? 10? 12?

Are you running programs that require 100% load on the processor and also need the graphics card to be running during meetings (a good example of this would be a game or compiling code)?


On a side note: 26 hours?

[hman]

Yes, the blog on the W520 said that 90W wasn't enough to recharge when running, but maybe it would work as you say with the lower intensity graphics card. This wasn't an easy choice, but after too long, you just have to make it and move on.

Regarding the travel, typically,when traveling to the orient, we won't stop. So, that' something like 14 hours for first plane leg, 2 or 3 hour layover, 2 to 3 hour second flight, then local travel - averages about 2.5 hours, so normally about 22 hours, but last time there were issues which added 4 hours. Of course, there's sleep during that time , but I easily went through both batteries on that trip, as they are old. I think that people travel like this all the time these days. Many are taking smaller machines with them, but I don't like that approach. The whole purpose for me in getting a desktop replacement machine is to use one machine for everything. I'm actually amazed at how well the present Thinkpad has filled this role for so long - great machines.Meetings abroad are mostly 8 hours, and grabbing a power outlet is often inconvenient, so it's good to know that the battery will hold in such situations. Same is sometimes true at home, but luckily not often. But the advantage at home is that I should never have to worry about bringing a power adapter again.

[hunterman223]

With all that battery power, you wouldn't have to pull out that big brick very often. If I remember correctly the 170w brick was either lighter than the 135w or not much more. Get a good backpack or messenger bag and you won't feel the extra weight. So basically the best of both worlds. The most future proof system with good battery life, where you don't need to pull out the big brick.


Sent from my iPod touch using Tapatalk

[Stucco]

I have the T520 i7-2720QM. I hooked it up to a Mini Dock Series 3 and used the accompanying 90W adapter. The laptop charged and functioned well, and running the turboboost monitor from intel didn't seem to reveal any difference in performance from the 135W adapter. It is possible that under intense power conditions the system may attempt to draw more than 90W, and damage the adapter in the process. Also, I have an SSD, so I am drawing slightly less power than a default configuration. YMMV

I *think* the first time I hooked it up to a 90W (directly) it failed to power the laptop and used the battery, but I have not been able to replicate that situation. I am currently typing on it, off the dock, hooked up to the 90W adapter, and everything is working well.

I ended up returning my dock because the audio port on the rear had a bad connector and the headphones were always full of static. I have not decided whether to repurchase the previous dock, or to upgrade to the Plus 135W model. The Plus has several more video adapters I would be able to take advantage of. Note that currently the 170W model of the Plus is slightly less expensive than the 135W right now, and it is indicated to be compatible with the quad code T520, however, the 170W adapter is keyed and will NOT fit into the T520, so that adapter would be a dock only solution.

[jvarszegi]

I don't think you will really see an improvement from the quad core for your stated uses. I think an i5-2520m would work just fine, and save you lots of cash.

If low weight and battery life are a priority, why not consider a dual-core T420? It's a bit lighter/smaller/thinner than the T520, can take a 65W ultraslim adapter, and still has a battery slice option with a ridiculously long runtime. The only real drawback is no higher-res FHD screen option available.

[wwcanoer]

I had the same question (but got no replies yet). http://forum.thinkpads.com/viewtopic.php?f=45&t=99683

Good to hear confirmation that the 90W can work on T520 i7-2720QM. The power usage is what scares me away from a W520. If I knew that a W520 could be switched to a "low power" mode and work like a T520 2-core on battery only or 65W/90W adapter, then I would choose that so that I have the power when needed but yet retain portability. The 135W and 170W adapter weight and size are quite significant!

@Stucco: Do you have a 65W adapter that you could try on your T520 QM?

If using a 65/90W power adapter can extend my battery life enough to get me through a traveling the workday and then fully recharge it overnight, then that is all I need.

FYI: Currently, dropping from i7-2620m to i5-2520 saves only $190 - 15% discount by phone = $161, which is significant, but yet only 15% of the notebook cost, so for me, it is worth it to know that CPU will not be a limiting factor and will last me for a few years.

Comment: It is disappointing how little information there is on the Lenovo website to truly select the best notebook for one's needs. The references that state the 4-core T520 is not compatible with the 90W adapter are not helpful if the truth is "not fully compatible - reduced power will limit CPU speeds."

[blackomegax]

You're so concerned with power and weight, why not get a T420 or X series? (both of which come with and function perfectly off of 65-watt bricks)

[wwcanoer]

Because I want the larger 15.6" screen.

Of course, I would like 17" in a 1 kg notebook but that won't happen this year.

[kpoman]

Guys, I am planning to buy a W520 right now with quadcore and quadro.
Can someone tell me:
- is the power supply bi-volt (100-240V) because I live in Brazil
- what is the weight of the power supply
- what is the battery life with low brightness and cpu in lower speed for a simple usage ?