W520 power supply rating vs. performance question

[ibmford]

Well, with ammeter, you measured the current drawn and assumed voltage is constant 120V. ;-) *wink * wink*

V x I=W but I think the BIG factor we ALL are overlooking is the DOCKING STATION POWER requirements.

The 170W power adaptor is supposed to power the DOCKING STATION as well as a QUAD CORE CPU and 2000 series QUADRO GPU. So there you have it, if you are going to use a DOCKING STATION with many USB devices attached and maximum laptop configuration (16-32GB DDR3 + Dual Harddisks with RAID 0) then you're going to need a solid power adaptor. Otherwise 135watt should be fine without a docking station.

[Volker1]

Now we know why the quadcore Apple macbooks (with their 85W power adapter) are discharging their battery while being plugged in if you dare to use CPU+GPU at the same time :-)

[davidhbrown]

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ibmford wrote:

Well, with ammeter, you measured the current drawn and assumed voltage is constant 120V. ;-) *wink * wink*

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Fair tease, since I forgot to think about the power supply's efficiency But I actually did measure the line voltage at the time... 122.2-122.4 on a "True RMS" digital multimeter (Fluke 112). This evening it's reading only about 118.4-118.6 (someone is showering... electric water heater must be on). I'm happy to report that refreshing the Windows Experience Index does *not* cause a drop in the line voltage

[ibmford]

Today I recieved my mini dock station 3 plus or what ever they call, It came with the same 170W power supply for W520. Using the system with docking station and multiple monitors at full capacity would justify the brick sized power supply's monster capacity.

Keep in mind these machines were built to milspec, with some margin for reliability etc...

Other than that 135W should be good enough for traveling...

[davidhbrown]

Has anyone actually used a W520 connected to a 135W adapter to see whether it complains like it does with the 90W adapter?

[aadiodavid]

I asked the original question after noticing that using a 135 watt brick did not cause error messages to appear or performance decrease on any benchmark. I am using the W520 daily for several hours on two different 135 watt supplies.

[ThorsHammer]

I stuck my 170w power supply back in the box.  It's 135w for me.

[ph_gregoire]

I do not understand this 170W power supply thing.

The old thinkpads (T61p for example) with same battery capacity and shorter battery live were able to run on a 85W power supply.

How come the W520 cannot, even if that were in degraded mode?

I don't understand how a W520 can last longer on the same battery capacity as a T61p and not work on 85W A/C while the T61p does???

[harrisb]

The 170W requirement is for a fully populated and utilized W520 with the 2000M GPU, the i7-2920XM processor running flat out at 3.5GHZ TurboBoost, all controls at maximum performance, 16GB RAM, all USB and eSataP ports utilized. The power demands in that scenario will exceed 135W, hence the need for the 170W supply.

Many have used the 135W without difficulties if they are using an i7-2820QM or lower. The 170W supply is a bit lighter than the 135W, but the shape of the 135W is easier to store in a travel case. Of course, it you just purchased the 9-cell slice battery and charge it up using the 90W slim travel supply (system can't be turned on in that scenario), you could just run totally on the batteries. The slice battery weighs just about the same as the 170W power brick..

[PanEuropean]

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davidhbrown wrote:

Has anyone actually used a W520 connected to a 135W adapter to see whether it complains like it does with the 90W adapter?

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I would be very interested in getting an answer to the same question that David posed above.  I travel internationally all the time with my W520, and if I could carry around a lighter power adapter (the 135 watt one, rather than the 170 watt one), I would be a much happier traveller.  My machine is a 4270 with the 'midrange' processor in it (2820QM) and I don't have a RAID installed.

Michael