Notebookcheck Test of the Latitude E6420

Test Dell Latitude E6420 Notebook - Notebookcheck.com Tests

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The temperature testing is extremely troubling. I do have to wonder if the mismatch between the bottom plate ventilation holes and the CPU has something to do with the heat issue? Hopefully, the current E6420 is just an interim model that will be replaced or updated within the next 6 months by an up-to-date model with native USB 3.0, build quality that is up to E6400/E6410 levels and adequate cooling for Sandy Bridge.

 

You must be right... Dell clearly put the ventilation holes in the wrong place! What were they thinking!?!

GK

 

Look at the screenshots in the review. That is 99c with Furmark AND Prime95 placing synthetic loads on both the CPU and GPU at the same time. This is a worst case scenario and can ONLY be produced through synthetic loading of the machine.

In "normal" use which includes games that heavily load both the CPU and GPU you will not see temps this high. You have to take Furmark with a grain of salt.

Putting the E6420 and E6520 (that both have the Quadro 4200M and both have the 2720QM processor) under the same load does show the tradeoffs between the 14" and 15" chassis. The E6420 heats up and cools down more quickly than the E6520. This is mainly due to the extra mass in the cooling system E6520. The fans are the same, but there are physically longer heat pipes in the E6520. The E6520 also has a larger area of magnesium in the base. Each machine will get into the 80s if you put a heavy processing load on them for an extended amount of time. The E6420 is more "spiky" with temps while the E6520 is smoother with temps but bulkier.

They might be closer to each other with dual core processors since they produce 10 fewer watts of heat. I know they will be closer without the 17 watts of the Quadro. Still, this much processing power in a 14" chassis is nice. Even with the Quadro and Quad core the temps are lower than what I was seeing in the previous Latitude generations.

 

No! No! No! Dell put the ventilation holes in the wrong place! We can clearly see that by looking at the bottom and noticing that they are not where they could be, like at the fan so that the air comes in and goes right back out instead of coursing over the CPU and heat pipe enroute to the fan exit.

GK

 

I take issue with your erroneous theory of thermodynamics. The issue real here is one of the most inexplicable, most obvious design mistakes that I've seen in years. Every Dell laptop I've ever owned has vent holes beneath the main fan. It makes sense. It increases airflow and decreases backpressure, allowing the cooling system to be more effective for a given amount of battery power. Now we have the E6420, where Dell decides not to have any vent holes under the fan. It's a very odd decision indeed, especially given the reputation for heat that the Sandy Bridge chips have acquired. over the last few weeks.

From the Notebookcheck review, which involved the least powerful CPU, I'd gather that cooling is indeed an issue, possibly a very serious issue for the heat produced by the 45 watt quad core CPUs.

Personally, if I had an E6420 on the way, I'd start looking for an extra bottom plate to do a bit of experimenting. It would be interesting to see if a few strategically placed holes under the fan would improve cooling. Of course, I'd suggest getting the second bottom plate to experiment with. I'd never want to drill holes in the bottom plate that came with the laptop, for all of the obvious reasons associated with the warranty. I'm sure that drilling holes in the bottom of your computer might invalidate the warranty, hence the need for a second bottom plate.

 

I believe that the power the fan consumes is directly proportional to the air it moves. So increased air flow would mean more battery power consumed. But still does not tell us if the net heat transfer is improved.

I'm inclined to suspect that moving the ambient air throughout the CPU and heat pipe areas offers better net heat transfer than allowing unventilated hot spots to develop around these heat zones that are located away from the fan.

I'm also inclined to believe that Dell tested their design and concluded where best to locate the air inlet. Sucking heat off the CPU with the heat pipe and air flow vs. just the heat pipe seems sensible to me.

GK

 

Another factor is the resistance along the flow path.

I agree. Usually, for example, there are some air vents near the RAM so it gets some cooling air.

John