Alienware's M18x, Part 2: AMD's Radeon HD 6990M in CrossFireby Dustin Sklavos on October 14, 2011 12:00 AM EST
The Alienware M18x Revisited
In our first run with the Alienware M18x, we sat down and took a look at the notebook itself along with NVIDIA's current top shelf mobile graphics part, the GeForce GTX 580M. We came away from the experience with mixed impressions of the M18x itself, a notebook that is by all means incredibly powerful but also seems to lose a lot of the balance that made the M17x R3 so desirable. On the other hand, the GeForce GTX 580M wound up being the fastest mobile GPU we'd yet tested, made only more formidable through the SLI configuration the M18x enables.
Today, Alienware has graciously provided us with the second half of the current top shelf performance equation in the form of a near-identically configured M18x, this time with two AMD Radeon HD 6990Ms in CrossFire. We'll also take a look at the Intel Core i7-2920XM's stock performance and compare it against the overclocked settings Alienware allows you to configure it with.
In a beautiful bit of synchronicity, our Radeon-equipped M18x also uses Alienware's black shell instead of the "nebula red" they equipped our GeForce model with. Other than that, this review unit is going to seem very familiar to those of you who caught the first part of our review. If you missed it, give it a read first.
|Alienware M18x Notebook Specifications|
Intel Core i7-2920XM
(4x2.5GHz + HTT, 3.5GHz Turbo, 32nm, 8MB L3, 55W)
(Overclocked to 3.5GHz, 4.2GHz Turbo)
|Memory||4x4GB Hynix DDR3-1600 (Max 4x8GB)|
AMD Radeon HD 6990M 2GB GDDR5 in CrossFire
(2x1120 stream processors, 715MHz/3.6GHz core/memory clocks, 256-bit memory bus)
18.4" LED Glossy 16:9 1080p
|Hard Drive(s)||2x Seagate Momentus 750GB 7200-RPM HDD in RAID 0|
|Optical Drive||Slot-loading Blu-ray/DVDRW Combo (HL-DT-ST CA30N)|
Atheros AR8151 PCIe Gigabit Ethernet
Intel Centrino Ultimate-N 6300 802.11a/b/g/n
IDT 92HD73C1 HD Audio
Stereo speakers with subwoofer
S/PDIF, mic, and two headphone jacks
|Battery||12-Cell, 11.1V, 97Wh|
|Front Side||N/A (Speaker grilles)|
Slot-loading optical drive
MMC/SD/MS Flash reader
2x USB 2.0
eSATA/USB 2.0 combo port
2x USB 3.0
S/PDIF, mic, and two headphone jacks
4x exhaust vents
|Operating System||Windows 7 Home Premium 64-bit|
|Dimensions||17.17" x 12.68" x 2.13" (WxDxH)|
Backlit keyboard with 10-key and configurable shortcut keys
Flash reader (MMC, SD/Mini SD, MS/Duo/Pro/Pro Duo)
1-year standard warranty
2-year, 3-year, and 4-year extended warranties available
Starting at $1,999
Price as configured: $4,224
There are a couple of major differences between this unit and our last one that are worth pointing out. First, while our GeForce-based system simply had a pair of 750GB 7200-RPM hard drives, this one has them configured in the RAID 0 that Alienware inexplicably seems to love shipping notebooks with. Don't ask me why, I just work here, but hopefully if I keep harping about this eventually they'll offer an SSD+HDD configuration in models that support it--the way they should have been doing for a while now. This is liable to affect PCMark scores somewhat.
The other major difference? The Radeons of course! While the AMD Radeon HD 6970M sported a slightly cut down Blackcomb GPU, essentially a downclocked version of the desktop Radeon HD 6850, the 6990M features a Blackcomb with all 1120 shaders enabled and a minor clock speed bump beyond the 6970M. Compared to the jump from the GeForce GTX 485M to the 580M, this is a bit more substantial of an improvement in raw hardware power. The 6990M features those 1120 shaders and a core clock of 715MHz (up from 680MHz on the 6970M, but down from the 900MHz of the desktop 6870), with 2GB of GDDR5 strapped to a 256-bit memory bus and running at an effective 3.6GHz (down from the desktop model's 4.2GHz clock.)
Since this M18x is otherwise identical to our previous system, we've eschewed retesting the screen and battery life, and our assessments of the unit's design and build quality from the previous chapter still apply. While the two differ in graphics configuration, Alienware uses muxes to switch the graphics hardware on and off, making any differences in running time academic at best. We've also opted to run our CPU-based benchmarks (and the 3DMarks) again using the i7-2920XM at stock speeds to compare performance against the maximum preset overclock Alienware makes available. The net result is a tremendous amount of new data for us to sift through.
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Alexvrb - Sunday, October 16, 2011 - linkMeaker is right. You can overclock it 100% and it doesn't mean beans if its throttling the heck out of it.
Meaker10 - Friday, October 14, 2011 - linkYou have the 6990M coming out behind the 6970M results....
JarredWalton - Friday, October 14, 2011 - linkThere are several factors at play. First, different drivers -- newer may not always be better, but without having both laptops and retesting, we can't say for sure. Second and more important by far is that the X7200 has a hex-core i7-990X. Even overclocked, the i7-2920XM can't always match it. Third, there's a difference in chipsets; the X7200 uses the X58 while the M18x uses the HM67. The X58 has tri-channel memory with two full x16 PCIe slots, where the mobile platforms go with dual-channel and two x8 PCIe slots.
While individually, each of these seems minor, taken together it's not too surprising to see the X7200 win some of the gaming benchmarks. Also notice that in more GPU-limited tests (Metro 2033, Mafia II, and STALKER at our Ultra settings), the 6990M CF setup outpaces the 6970M CF by a fairly large margin. Most of our other titles, even at max settings, may not completely saturate the GPUs.
Meaker10 - Friday, October 14, 2011 - linkWhile I agree for the most part, if we were CPU limited we would see a hard wall, the CPU utilisation is close between AMD/Nvidia so that while there can sometimes be gaps they are not large.
Well looking at the highest setting Dirt 2 benchmarks we see:
580M in the lead on the back of the 2920XM over the x7200 setup by 15%, a lead that suggests no GPU bottleneck.
Now looking at the M18X the 6990M crossfire is getting 77% of the FPS of the 6970 setup. Usually crossfire is less limited by PCI-E lanes than SLI.
Usually drivers can alter results, but if we project where the 6990M crossfire results should be then they are underperforming by around 30%, not something you would expect in newer drivers.
Have you checked the card's were not throttling during this run? Looks a bit suspect to me.
Meaker10 - Friday, October 14, 2011 - linkSorry I meant to say it indicates no CPU bottleneck.
JarredWalton - Friday, October 14, 2011 - linkI'll ask Dustin to check on the clocks and thermals of the AMD 6990M, as well as the i7-2920XM -- both could potentially throttle. I'll ask him about AMD driver version as well. Also, while on the desktop the SLI and CF results are often similar in terms of CPU utilization, on notebooks all bets are off. Every time I've played with an SLI or CF laptop, I've always felt like performance was never quite where I'd expect for the given hardware.
For instance, SLI and CF scaling on desktops compared with scaling on notebooks seems like it usually doesn't do nearly as well on notebooks. I'd have to go analyze some hard numbers, but it's just been my impression. Another example is when you launch a game on an SLI or CF notebook, the display usually seems to flicker on and off for 10 seconds. Maybe that's been fixed now, but the last time I tested it I seriously thought, "WTF is going on!?"
In theory, everything should be the same, but when you go mobile it rarely feels that way. Yet one more reason to recommend the M17x or ASUS G74SX over the M18x.
Meaker10 - Saturday, October 15, 2011 - linkI have a 16F2 barebone myself (GT683R based).
It would be interesting to face the x7200 and M18x against each other. Recording a baseline one card performance and looking at the mobile vs desktop chipset scaling with the same drivers and cards.
ik9000 - Saturday, October 15, 2011 - linkre your comment that the premium for a single 580 isn't worth it over the 6990. While dual GPU set-ups don't offer optimus, with a single card isn't this an option? Would Optimus give a single GTX580 machine a better battery life than a single 6990?
iamlilysdad - Saturday, October 15, 2011 - linkIt appears that Dell now lists a 256gb + 750gb option for custom configuration for the M17X R3. Guess that's another plus in the column for the "little" brother.
Akv - Sunday, October 16, 2011 - linkAnother "gaming laptop". Yawn...
Sorry to repeat that every six months, but I am part of the population who have all the necessary large gaming equipment at home (screens, cases, fans, mice, keyboards...) and who use their laptop when traveling.
In that sense the prospect of gaming with a laptop seems to me appalling compared to what my desktops can offer, and the prospect of using a low-power, low-noise, light-weigth laptop with excellent screen and excellent speakers seems highly appropriate.