Is it worth upgrading from i7 3840QM to i7 3940XM on HP 8770W?

What is your opinion, would you do such an upgrade?

 

See:
https://www.cpubenchmark.net/compare/Intel-i7-3840QM-vs-Intel-i7-3940XM/900vs1482

Why? Not only are you increasing the TDP by 10W or 22%, but you are also only moving sideways on the overall performance scale (vs. any modern processor).

Keep a working system as-is and enjoy as long as possible. Just because upgrades are possible doesn't mean they should be done.

And my reasoning above is at $0 cost too. When you take into consideration the $$$, time and risk of doing such an upgrade, it is even less desirable, IMO.

What is your reason for requiring more firepower? Gaming or paid work? Both? You'll have to weigh the cost/benefits for yourself.

 

Many potential issues
CPU cooling (do you have headroom)
Can the VRMs handle it (what do others achieve in your model)
Is the BIOS sufficiently unrestricted

I'm testing my custom watercooling project with 3940XM @ 4.6ghz, a decent improvement over the un-powerlimited 3740qm @ 3.9ghz which is itself a big jump over stock, but that is using an insane level of cooling and an unlocked+modded main bios (on a platform that has significant headroom e.g. I've previously shoved over 500W through it - over double the stock config - via power modded GPUs) which are things that I'm guessing you won't have on your HP.

 

The i7-3840QM is already partially unlocked (4 turbo bins), which means it can be overclocked to 4GHz on all cores using ThrottleStop or XTU. A 3940XM might be able to go slightly further, at the cost of much higher demands on system cooling and motherboard/PSU power delivery, which your system may not be able to support. Since pre-Haswell mobile CPUs don't expose fine-grained voltage controls, you're kind of at the mercy of whatever voltage table is programmed into the chip, which is almost assuredly too high. So all in all, I don't think upgrading to an XM in your particular situation is worth it.

 

Unfortunately any O/C is not possible on 8770W - locked on a bios level. So no XTU, Throttlestop etc.
I wanted to squeeze the max out of my 8770, but maybe you are right - 55W will be a lot of heat and the performance gain won’t be so big probably. Now my 3840QM is maxing out at 72-74C both CPU and GPU heavily loaded.

 

then its probably not worth it unless you are looking at a very cheap cpu here.

 

I wouldn't recommend it. My 3920xm gets toasty, even with liquid metal applied to both it and my M5000M. It rarely throttles but I think it negatively impacts my ability to OC the M5000M. If I want to put a decent OC on my M5000M or do a long gaming session at a LAN event I end up using an OPOLAR cooler to keep everything from throttling.( https://www.amazon.com/gp/product/B01NACVLWM/ref=ppx_yo_dt_b_asin_title_o01_s00)

 

What are your CPU/GPU max temps under heavy load?
I applied LM to my 3840QM and the temps are 70-71C under Prime95/Aida64 Stress test/XTU Stress test and 75-77C under heavy 3D load together with GPU (same as yours- M5000m OCed 1200/2700, 0,987V, 67C max temp)
As my GPU is still on Kryonaut, I intend to apply LM on it also, as I want to use it with Prema vBios which allows me to rise the clocks to 1400/2700 at 1.087V, but on Kryonaut the temps are rising up to 88-90C with this vbios...

 

Both CPU and GPU will creep past 80 on heavy load - I don't remember how high the GPU goes if left unchecked but it definitely begins to throttle. If I use the external cooler it stays significantly cooler - I'll have to test and let you know for the exact figures. I'm currently running the M5000M with the core just over the 980m boost (maybe 1130-1150? Can't recall and at my desktop currently). Mind you, this was with 2 full tear down and repaste of LM on both GPU and CPU along with fujipoly pads (explanation below). In any case, I think my cooling fan may be worn / not working at 100%, part of the explanation for those higher temps, but I also think the 3920 contributes to the problem.

I ended up applying LM 3 times thanks to those fuji pads, which I wouldn't necessarily recommend for LM. I used fujipoly for GPUs before with kryonaut and never had an issue. Didn't occur to me at the time but the fuji pads have very little "give" to them and created very slight tolerance issues where the heatsink was not tight against the GPU. Much less of an issue if you are using a blob of paste, but with LM being such a light/thin application, it becomes an issue and caused worse temperatures than the previous kryonaut until I swapped the fuji pads for thinner ones.

 

If you overclock with coreboot, sure.

 

Just to say I took the risk and bought 3940XM for my HP 8770W and most surprisingly it runs cooler than my previous 3840QM! By 4-5C!
Same setup, same thermal compound.
Where 3840QM hits 89-90C, 3940XM reaches 85-86C....go figure... I think it is silicon lottery.
Very happy with the upgrade!

 

XM is better binned than QM, and can hit the same or higher clock speeds at lower voltage.

 

Yes, indeed!
And where the 3840QM did throttle a bit after a while during stress test in XTU (3.6=>3.4GHz), 3940XM keeps constantly at 3.7GHz!
The only downside is that I hoped for 2133MHz DDR3, but still 1866MHz CL9 is my limit. May be it is the motherboard, which doesn’t contribute enough to get to this speed...

 

I don't think its worth it.
You'd be increasing the TDP by 10W (which can be surprisingly unforgiving for various laptops as their cooling wouldn't be able to cope with it, often leading to overheating) for a relatively small bump up in performance (100-200MhZ extra is quite literally nothing noteworthy - you won't really notice much/any difference).

My own laptop (PH517-61) seems to drop RAM speed to 2133MhZ when all 4 RAM slots are used (which is not exactly encouraging as I was hoping it would stick to 2400MhZ at least). I don't think it has much to do with the motherboard because it should be more than capable of running the RAM at even 2933MhZ (if I were to use that RAM speed), however, laptop OEM's don't usually program the BIOS to max everything out.
In fact, even though my mobo is B450, Acer's BIOS is very constricting/limiting, so its not really robust enough to allow the RAM to run properly when all 4 slots are used (I'd need to use Ryzen Master to increase the speed to 2400MhZ at least).

Anyway, I suspect the same thing might be happening on your laptop... you could also check if you're running latest BIOS (if not, the OEM may have released a BIOS update which fixes this issue on your laptop - although, make sure you can restore the BIOS to an earlier version/aka BIOS recovery in case the update doesn't take for whatever reason).

 

Earlier version of bios is not possible on EliteBook 8770W. Downgrade is not allowed by HP.

 

I wasn't suggesting a downgrade.
I was suggesting to UPGRADE the BIOS. Check HP website to see if they released any new BIOS updates.

 

I am with the latest bios release...

 

Seems like a BIOS issue in that case... either that or you're running mis-matched sticks.

 

Two pairs HyperX...
I think 32GB is too much load on the memory controller for 2133..

 

Yes, 4 sticks is more stress on the IMC than 2.

 

Guys,
I have two 3940XMs
One needs 1.196V for its native speed (3.7GHz all cores), the other one needs 1.226V
Both with LM applied, the first one (1.196V) reaches 89C on one of the cores with temp difference between the cores 5-6C.
The second one (1.226V) reaches 88C with temp difference between the cores - 1-2C
Which one would be the keeper?