Precision 5520 i5-7300HQ (TDP 35w) vs i7-7820HQ (TDP 45w)

Hi, first post for me.

I am about to buy the Dell Precision 5520 (FHD, 16gb, 256gb, 97w battery) but i'm uncertain which processor to go for. I will be using it mostly for normal stuff (browsing, watching movies, pictures), but sometimes work (AutoCad 2D stuff, Adobe CC, Rhino, SketchUp).

I would like a laptop that runs cool, low noise. Will the i5-7300HQ 35w run cooler than the i7 45w? Most applications I will be using don't take advantage of hyperthreading, am I correct in asuming the i5 will do the job almost just as well as the i7? What difference does it actually make that the TDP changes from 45w to 35w?

PS: the price difference between the i5-7300HQ and i7-7820HQ is 200$ (in Denmark, where I will be buying). These are the only two options available, besides the Xeon.

 

Given that Kaby Lake is only a small advance on Skylake I attach a couple of graphs showing CPU speed - power relationships for the i5-6440HQ and the i7-6820HQ.


I'm in a similar situation to you and was happy with the performance of the i5-6440HQ when I had the Latitude E5570 and, when I replaced that notebook with the Precision 5510 (I couldn't get on with the E5570's keyboard offset due to the numpad) I disabled hyperthreading on the Precision (which came with the i7-6820HQ from Dell Outlet) in order to keep the fan a little quieter (it stays off completely under light usage). I wouldn't spend the extra money on the i7 unless I know that the 8 thread capability will be needed.

John

 

Based on my experience with those programs, you'll be fine with the i5.

 

Thanks for answers!
Do you know if/how the 35w TDP will influence heat or throttling?

 

Based on my Skylake experience (see the graphs above) 4 cores fully loaded will be well within the 35W TDP (and your workload is unlikely to fully load 4 cores). The worst case for TDP is full CPU load plus full internal graphics load (in which case something will throttle to stay within the TDP). However, that situation shouldn't happen as any 3D graphics (not a significant feature of your workload) will be handled by the dGPU.

The only thing I would note is that you won't see the full Turbo speed very often. That speed is only when one thread is running and background processes + workflow will usually combine to keep two threads fairly busy. The basic rule is: one core = full speed; two cores = full speed - 100MHz, two cores = full speed - 200MHz, etc. That's by design and not the same as throttling.

John

 

Veering off topic ever so slightly here but did you consider the numpad-less E5470 when making the switch, or was it a case of not wanting to downgrade to a smaller screen? I'm kind of picking between E5470 with i5-6440HQ, E5470 with i7-6820HQ and M5510 with i5-6300HQ; E5470 has the trackpoint I greatly prefer over trackpad, but M5510 would bring the dGPU which although not essential, would be neat for those late-night gaming sessions when staying in a hotel etc.

 

I bought the E5570 because my old eyes started complaining about the screen size on the E7450 (in other respects a very nice notebook) so I moved to something bigger and, at that time the 5510 wasn't available at a price I was willing to pay.

The 5510 has the bigger, and better quality, FHD screen (slightly less anti-glare coating which gives a sharper image plus slightly wider gamut). The 5510 has less keyboard travel than the Latitude and the latter is nicer for lots of typing. The E5470 also has the PgUp / PgDn keys which the 5510 lacks. However, the 5510 with the big battery option will outrun the E5470. I think the E5470 is available with a fairly weak AMD dGPU but you lose a RAM slot. The E5470 has a slot for a WWAN card if that's on your wish list. The 5510 also comes with a chunky 130W PSU (but will work with a 90W PSU via a 7.4mm to 4.5mm adapter). The non-dGPU E5470 is happy with a 65W PSU.

John

 

Thanks John, good insights, appreciated. Not being able to purchase from the Dell outlet adds a layer of trickiness to this whole process but like I always say, if it was easy, everyone would be doing it.

Sorry for borrowing your thread, bobhundrvk, it seems the quad-core i5 would be the sweet spot cpu-wise for our respective needs and usage scenarios, and that the pecularities in documented TDP isn't likely to be of practical relevance; I had noticed the same thing regarding 35W vs. 45W when reasearching E5470 and I thought it might be cos of the fact that the i5 was available in combination with a dgpu, and that the cpu was limited at 35W in order to keep the system consumption in check, whereas the i7-6820HQ was only available with igpu graphics and could be allocated a larger slice of total resources. This theory can be binned now as the M5510/M5520 configurations don't adhere to such artificial rules regarding gpu options.

 

No problem, it's interesting for me as well. I'm going back and forth between i5 and i7, but also between 5510 and 5520, trying to find a good deal. I think either of those solutions will work fine. Thanks, John, for the help