Dell Precision M3800 Owner's Review

If you, you know, looked at the photos of the XPS15/M3800, you will indeed find out that it does not have a numpad....

 

Still, one of my biggest concerns is the slower CPU in a workstation. While starting off with a 2.2 Ghz isn't bad, I would be really strange not to have a 2.7 or 2.8 option. There are numerous consumers notebooks who already have these speeds. After all, the press release stated clearly that the M3800 is an alternative to the Macbook Pro. But how can it be an alternative if two of the three options are with either a 2.3 or 2.6 base configuration? The lowest speed in a M4800 and the M6800 is a 2.5 Ghz,

This is all speculation. I don't think dell can afford to have just one CPU and as low at that too.

 

MBP(r) has issues with throttling and chassis getting hot under heavy load. Cpu can only enter turbo states for extremely short periods of time and then unless you let it "cool off" you wont see them again.

While the little m3800 works like this:

Its not just about "pumping" in high end cpu without consequence - workstations should be stable even under heaviest loads and keep its thermals in check. I dont think MBP has problems with stability but throttling and hot chassis will cause unwanted consequences on other internal components in the long run.


Family member had MBPr with IB cpu and during some video renderings it would get insanely hot - and throttling would become obvious. MBP is an awesome machine but its not a work horse.

 

So basically what you are saying is that you can run the M3800 for long periods of time reaching it's maximum 3.2 Ghz, while the the MBP wouldn't reach 3.8 Ghz due to immediate throttling ? That would be a major oversight for a company that markets itself as the perfectionist.

What is the maximum CPU you can use without the throttling factor? 2.3?

 

Possibly there isn't much info about this out there. In that thread, most people suggest that throttling happens more because of the thermals rather than the wattage of the adapter. Old models consumed from the battery if it required more watts but I believe the new one doesn't.

Anyway, I don't think a Dell m3800 would be better thermally if it could also have the 4960HQ. After all, aluminum is a tiny bit better for cooling and the dimensions are almost the same. Thus, if it's better thermally, that's because of the IGZO panel consuming less,t he processor consuming less and the k1100m consuming less.

 

I would take a m3800 with a lower end cpu that does not throttle/overheat under heavy loads over a macbook pro with a faster cpu that does throttle and overheat.

I think the cpu that the m3800 has is fine.

 

If you install the Intel XTU software, the max turbo clock rates are unlocked. One active core can go to 3.4Ghz, Two cores go to 3.3Ghz, Three and Four go to 3.1Ghz. You can't adjust the amount of power that the processor gets, so the higher turbo modes have to stay within Dell's 46.25 watt spec for short term turbo (around 40 seconds) and 37 watts for long term turbo. Turbo clock speeds will be adjusted down until they fall within the power limit of 37 watts on the CPU.

You won't go past 37 watts in turbo mode until you get to 4 (of 8) threads running in Prime95. Single threaded applications will stay at 3.4Ghz forever since they are no where near hitting 37 watts You will see some quick dips to 3.3Ghz as the thread is passed back and forth between processors.

WIth 8 threads running, all 4 cores are fully loaded, they run between 3.0 - 3.1Ghz for around 40 seconds, then fall back to 2.6 - 2.7Ghz. They will stay between 2.6 - 2.7Ghz with a temp of 78C until you remove the CPU load. The M3800 never allows the CPU to fall back to the base 2.2Ghz as long as a the processor is fully loaded. The fans stay quiet.

If you then add MSI Kombustor to fully load the GPU in addition to the fullly loaded CPU, several things happen. Temps on the CPU will jump from 78C to 84C followed by both fans kicking in. At this point you will hear the fans for the first time. The temp on the CPU will fall back to 81C and the temp on the GPU will climb to 69C. The CPU will lock in at 2.6Ghz and stay there. Battery charging rates will fall from 20Whr to 16Whr. The system will stay in this state for as long as you want it to.

If you stop MSI Kombuster, the temp on the CPU falls from 81C to the mid 70s. The fans also slow down. Once the CPU hits 69C, the turbo mode starts going back up to switching between 2.6 and 2.7Ghz while the fans continue to slow down. Eventually, the system settles back to the same CPU behavior as before, but the temp will stay around 70C instead of 78C. The CPU stays cooler because the fans don't completely slow down to low speed until the system is below 50C or so. While the CPU is staying right at 70C with a full load, the fans stay at medium speed.

Here is the problem with everything I just typed - this is still a pre-release machine. Dell has plenty of time to tweak the BIOS and performance curves. All of this could change by the time the M3800 ships. Maybe they could add some time to that short term turbo boost.

 

Wow! Thank you for such a detailed explanation, Bokeh! It is really helpful to understand what's going on behind the scenes!

 

That's actually quite amazing Bokeh! Do you think always staying at 2.6 turbo is a design decision and thus part of the spec or that you just got a great processor batch? I know from overclocking experience that some processors run cooler and can overclock significantly higher than others. Before I tried overclocking, I had assumed they'd all be exactly the same. EDIT: OK, you're right it's pre-release so we won't know for sure. I hope it's part of the spec.

Anyway, I'm pretty much convinced that the MBP cannot handle loads for extended periods with the same grace. It's pretty remarkable that the fans stay quiet while stressing all 4 cores. I never owned a MBP before but my old Macbook would quickly become noisy under load. My Macbook Air does too actually but not quite as bad.

The fact that the m3800 can continue to charge the battery while dishing out that much performance is pretty impressive and it means that the wattage of the adapter is never going to be a bottleneck. For the MBP, I read on the Macrumors forums that it could tap into the battery for older models. That's worrying if you intend to actually use the full performance your computer offers and if you also want to maintain portability at the same time!

I'm getting the m3800 for sure now since apart from work, I like to do chess analysis on my laptop and that uses all 4 cores to the max. The only downsides that even remain are
1. Windows DPI scaling probably not being quite as well supported by non-Microsoft apps (should become less of an issue with time) and
2. No 1TB PCIe SSD. However, I'm guessing there will eventually be 1TB SSDs and that the extra speed from PCIe will only be relevant when moving large files. Plus, the lack of upgradeability kind of offsets the benefits. Furthermore, I trust NTFS more since I think HFS+ does only metadata journaling.

 

Bokeh-
Did you ever get a chance to confirm whether the HDMI port can be used to drive a u3014 or u2713 at native resolution while also running the same/similar screen on displayport AND the native LCD? I'd like to run two non-daisy chained large screens plus the laptop's lcd if possible, typically the bottleneck here would be HDMI.

Thanks!