Posted:2006-05-18 By hardware review Number of View:29597
INTEL PENTIUM D 820 AND 670
PROCESSORS REVIEW BENCHMARK
OVERCLOCKING
By :hardware review
Posted:2006-05-18
xtreview is your : Video card - cpu - memory - Hard drive - power supply unit source
Intel Pentium D 820 and 670 processors Review Benchmark Overclocking
IT'S THE GEEKY equivalent of a conversation that most guys would have about a Maxim girl versus the Olsen twins. Would you rather have a single, very fast CPU or a pair of somewhat slower processors? That's a tough question, and it's precisely the one that Intel has prompted by releasing a couple of new CPUs today, the Pentium D 820 and the Pentium 4 670. The P4 670 is the fastest single Pentium 4 processor ever released, running at nearly 4GHz. The Pentium D 820, meanwhile,
runs a full gigahertz slower, but it has two complete Pentium 4-style CPU cores onboard for a very nice price.
Two new Pentiums roll out In many ways, the two CPUs Intel is introducing today are fundamentally similar. Both are based on the latest version of the Pentium 4's Netburst microarchitecture, both ride on an 800MHz front-side bus, and both are capable of 64-bit computing via Intel's EM64T extensions. But beyond these wide areas of overlap are deep differences in approach.Which is better? Well, that depends on a great many things. Let's have a look at some of them.
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The Pentium D 820 (left) and Pentium 4 670 (right)
The Pentium 4 670 is arguably the last of an old guard, a CPU intended to extract maximum performance out of a single processor core. The P4 670 extends the familiar Pentium 4 600 series one more speed grade, to 3.8GHz, and like the rest of the 600 series, the P4 670 packs 2MB of onboard cache to further improve performance. For the privilege of owning a CPU that runs at this dizzying speed, you'll have to pay something close to Intel's list price of $851.
The cores on the Pentium D 820 pulse along at a relatively leisurely pace of 2.8GHz, but there are two of 'em, so its overall performance in multithreaded applications or when multitasking may be superior to a single-core CPU. We've already reviewed the Extreme Edition of Intel's dual-core desktop chip, code-named Smithfield. The Pentium D is a de-tuned version of the Smithfield core that's had its Hyper-Threading capabilities disabled and its clock speed dialed back a few notches to 2.8GHz. In fact, its
clock speed is sufficiently slow that Intel apparently saw no need for the 820 to have power management features like Enhanced Speedstep, the C1E halt state, or TM2 thermal throttling. Other recent Pentium desktop processors run at 2.8GHz when throttled back, and the Pentium D 820 is already there.
The real virtue of the Pentium D 820 isn't just its dual processor cores, though; it's the price. At only $241, the Pentium D 820 signals that Intel is dead serious about bringing dual-core CPUs to desktop PCs. In fact, the Pentium D's price is low enough to shake up the whole CPU market. Its arrival presents consumers with a series of stark choices between single-core and dual-core processors at roughly comparable prices.
That fact, combined with the proliferation of very different model numbering systems from AMD and Intel, has made head-to-head competitive comparisons of CPUs quite a bit trickier than in the past. Freed from the constraints of model number-clock speed comparisons, Intel and AMD have priced their CPUs at points that don't entirely correspond to one another. I've made an attempt, in the table below, to classify competing CPUs in a reasonably direct manner, but I may have only succeeded in illustrating the
problem.
CPU
Price
CPU
Price
CPU
Price
CPU
Price
Pentium 4 630
$224
Athlon 64 3200+
$194
Pentium 4 640
$237
Pentium D 820
$241
Athlon 64 3500+
$272
Pentium D 830
$316
Pentium 4 650
$401
Athlon 64 3800+
$373
Pentium D 840
$530
Athlon 64 4000+
$482
Athlon 64 X2 4200+
$537
Pentium 4 660
$605
Athlon 64 X2 4400+
$581
Pentium 4 670
$851
Athlon 64 FX-55
$827
Athlon 64 X2 4600+
$803
Pentium 4 XE 3.73GHz
$999
Pentium XE 840
$999
Athlon 64 X2 4800+
$1001
That's official pricing on the Pentium D line, by the way.
You can see the trouble. Identifying a direct competitor for some of these models, like the Pentium D 830 or the Athlon 64 4000+, is downright befuddling. Fortunately, the two processors we're reviewing here line up fairly directly against the competition. The Pentium 4 670 is priced pretty close to the Athlon 64 FX-55, and the Pentium D 820 just undercuts the Athlon 64 3500+ by $31. That means, of course, that the Pentium D 820's two somewhat pokey cores will do battle with a relatively quick single-core
competitor from AMD.
This is what I meant by stark choices. AMD doesn't offer a low-end dual-core processor and apparently doesn't plan to do so in the near future. For many single-threaded tasks, one of the Pentium D 820's 2.8GHz cores should be sufficient, but it's hardly quick by current standards—especially when you consider that the long pipeline of the Prescott/Smithfield cores means lower clock-for-clock performance. Intel also offers the Pentium 4 640 at the same basic price, but there's no way a single-core Pentium
4 at 3.2GHz can match the Pentium D 820 overall. I'm getting ahead of myself, though. We'll let the benchmarks tell that tale.
Intel's D95GTP motherboard sports a VGA port and a single PCI-E x1 slot
The 945 series' ability to support DDR2 667 memory may be most beneficial to the performance of the 945G, whose built-in graphics core will have access more memory bandwidth. In the 945G, Intel has massaged the GMA 900 graphics core from the 915G and given it a new name, the GMA 950. The GMA 950 still has a four-pipe design, but clock speeds are up from 333MHz to 400MHz. These tweaks are sufficient for Intel to claim a 100% performance improvement over the GMA 900 in 3DMark05. The GMA 950 also adds the
ability to connect to a media expansion card, useful for such things as adding a TV tuner to one's system. (The 945P lists for $38 in quantities of 1000, and list price on the 945G in 1K quantities is $42. So the price of a GMA 950 is effective $4. That, folks, is how Intel got the be the world's #1 graphics supplier in terms of volume.)
The other end of the chipset equation has changed, too, with the introduction of Intel's ICH7 and ICH7R south bridge chips. The ICH7 series has two more PCI Express lanes than the ICH6, bringing the total up to six. Both ICH7 chips also support Serial ATA's new 300MB/s transfer rates (or 3Gb/s, if you must), but only the ICH7R has Intel's Matrix Storage. The Matrix Storage package includes RAID capabilities, new RAID levels 5 and 10, and support for the AHCI specification. Without AHCI, the non-R version
of the ICH7 will be devoid of support for Native Command Queuing (NCQ) and hot-plugging of devices. For that reason, I'd expect even some mid-range 945P-based motherboards to use the ICH7R, as Intel's D945GTP does.
Review Intel Pentium D 820 and 670 notes
We have focused our testing today on the question of thread-level parallelism, in part because we believe that is the most important performance question one can explore in relation to multi-core processors. However, we are excited about the possibilities for better multitasking that may come with dual-core CPUs, and we'd be glad to take your suggestions for testing multitasking scenarios.
Also, we have included results for the Pentium D 840 in our testing, which we obtained by disabling Hyper-Threading on our Extreme Edition 840. Since the Pentium D 840 is just an Extreme Edition 840 sans HT, the numbers should be valid. Similarly, the Athlon 64 3500+ scores you'll see in the following pages were obtained by underclocking an Athlon 64 3800+ (with the new "Venice" core) to 2.2GHz. The performance should be identical to a "real" 3500+.
Our testing methods
As ever, we did our best to deliver clean benchmark numbers. Tests were run at least twice, and the results were averaged.
Integrated ICH7R/STAC9221D5 with SigmaTel 5.10.4456.0 drivers
Integrated ICH7R/STAC9221D5 with SigmaTel 5.10.4456.0 drivers
Integrated nForce4/ALC850 with Realtek 5.10.0.5820 drivers
Graphics
GeForce 6800 Ultra 256MB PCI-E with ForceWare 71.84 drivers
OS
Windows XP Professional x64 Edition
OS
updates
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What's new Intel's new CPU core packs fistful of enhancements over the original Prescott core. I'm gonna bust out the bullet points in order to give you the highlights.
2MB of L2 cache — In terms of performance, this is the number-one change. The 600 series and the new Extreme Edition both pack a robust 2MB of L2 cache now, twice as much as older P4s. The extra on-board cache memory will boost performance in situations where the CPU can avoid accessing slower main memory in order to complete a task. The benefits of extra cache RAM aren't universal, though. Some programs cycle through quite a bit more data than 2MB, and won't benefit from additional cache. Others
already fit nicely into a smaller cache, and therefore aren't helped by more of the same. We'll explore this dynamic in our performance tests, of course.
The addition of another meg of L2 cache raises the new core's transistor count to roughly 169 million, well above the 125 million transistors in the original Prescott core. Thanks to Intel's 90-nanometer manufacturing process, the chip isn't incredibly large by today's standards. Die size is up from 122mm2 to 135mm2. Larger chips generally tend to consume more power and generate more heat, all other things being equal. In this
case, though, other things are not entirely equal.
Enhanced power management — The 600 series finally brings Intel's Enhanced SpeedStep technology to the desktop. Previously used in Intel's mobile processors, SpeedStep dynamically scales CPU clock speed and voltage in response to load. The new core also includes the enhanced halt state from the Pentium 4 500J-series processors we reviewed not long ago. I'll explain more about how these new power management features interact shortly.
64-bit extensions — Intel has dubbed its 64-bit extensions EM64T, for Extended Memory 64 Technology, but they are really just a functional clone of AMD's AMD64 extensions, first implemented in the Opteron processor a couple of years ago. With these extensions and the right software, including a 64-bit operating system and applications compiled to use 64-bit extensions, the Pentium 4 gains the ability to address more than 4GB of RAM (without any workarounds). AMD64 and EM64T also include some additional
registers, or local slots on the chip for storing data, that should provide a bit of a performance boost in 64-bit applications. The move to 64-bit computing won't bring revolutionary new heights of CPU performance overnight, but it will prevent us all from bumping our heads on the 4GB memory address space limitation in the next few years.
Execute Disable Bit support — Like the 500J series processors, the new Intel core includes support for the Execute Disable Bit, also called the No Execute (NX) bit by AMD. Operating systems can use this "no execute" capability to help minimize the risks of certain types of security threats, such as buffer overflow exploits.
Notably missing from the features list of the 600 series is support for faster 1066MHz front-side bus speeds. Instead, the P4 600s will roll on an 800MHz bus,
as did their predecessors. The 1066MHz bus is reserved for the Pentium 4 Extreme Edition processors.
Speaking of which, the Pentium 4 3.73GHz Extreme Edition is quite a change from the 3.46GHz model. This new Extreme Edition is based on the same Prescott-derived CPU core as the 600 series, while previous Extremes were based on the pre-Prescott "Gallatin" core. That means the new Extreme Edition now has a longer, 31-stage main pipeline and lower clock-for-clock performance. The old EE's L3 cache is gone by the wayside, replaced by the beefy 2MB of L2 cache in this new core. The new EE can also do
the 64-bit dance, but it doesn't have the fancy power management or enhanced halt state that the 600 series does. The EE 3.73GHz ought to outperform the 600 series thanks to its 1066MHz bus and higher clock speed, but whether it can outperform the EE 3.46GHz is another question.
Benchmark results
Memory performance
The first few tests are synthetic memory tests. They aren't a good indication of real-world application performance, but they can illustrate the impact of larger L2 cache on the memory subsystem.
Doom 3 Benchmark
We'll begin the real-world tests with Doom 3. We tested performance by playing back a custom-recorded demo that should be fairly representative of most of the single-player gameplay in Doom 3.
The extra cache raises performance by a few frames per second in Doom 3, but that's it. The Pentium 4 needed more of a boost in order to become competitive.
Far Cry benchmark
Our Far Cry demo takes place on the Pier level, in one of those massive, open outdoor areas so common in this game. Vegetation is dense, and view distances can be very long.
Far Cry barely notices the extra cache at all.
Unreal Tournament 2004 benchmark
Our UT2004 demo shows yours truly putting the smack down on some bots in an Onslaught game.
UT2004 doesn't seem to care much for the additional cache, either, and the new Prescott-based Extreme Edition has trouble catching up to the old one here.
However, could the picture change during actual gameplay? Some folks from Intel suggested to us that we should consider testing gameplay performance with the FRAPS frame rate capture program instead of relying on an in-game benchmarking function. The suggestion makes some sense, because timedemo playback tools don't always use every aspect of the game engine, such as physics, A.I., and user input routines.
I tried using FRAPS with a couple of games, including Doom 3 and Rome: Total War, but frame rate caps in those games prevented us from being able to show meaningful performance differences between different processors. UT2004, which is very much a CPU-bound game, was a different story. The results below are averaged from five different 150-second gaming sessions played on the same Onslaught map as in our timedemo above, ONS-Torlan. I was playing against computer-controlled bots, so UT2004's A.I.
was working overtime.
3DMark05 benchmark
Finally, we have a benchmark that seems to appreciate the additional cache! 3DMark puts it to good use, bolstering the P4 660 and EE 3.73GHz to the top ranks of its overall CPU index.
Video encoding and editing
XMPEG DivX video encoding We used the default settings for the DivX codec to encode a 3000-frame sequence from a DVD-formatted MPEG2 source file.
SiSoft Sandra Benchmark
Next up is SiSoft's Sandra system diagnosis program, which includes a number of different benchmarks. The one of interest to us is the "multimedia" benchmark, intended to show off the benefits of "multimedia" extensions like MMX and SSE/2. According to SiSoft's FAQ, the benchmark actually does a fractal computation:
This benchmark generates a picture (640x480) of the well-known Mandelbrot fractal, using 255 iterations for each data pixel, in 32 colours. It is a real-life benchmark rather than a synthetic benchmark, designed to show the improvements MMX/Enhanced, 3DNow!/Enhanced, SSE(2) bring to such an algorithm.
The benchmark is multi-threaded for up to 64 CPUs maximum on SMP systems. This works by interlacing, i.e. each thread computes the next column not being worked on by other threads. Sandra creates as many threads as there are CPUs in the system and assignes [sic] each thread to a different CPU.
We're using the 64-bit port of Sandra. The "Integer x16" version of this test uses integer numbers to simulate floating-point math. The floating-point version of the benchmark takes advantage of SSE2 to process up to eight Mandelbrot iterations at once.
Power consumption
We measured the power consumption of our entire test systems, except for the monitor, at the wall outlet using a Watts Up PRO watt meter. The test rigs were all equipped with OCZ PowerStream 520W power supply units. The idle results were measured at the Windows desktop, and we used SMPOV and the 64-bit version of the POV-Ray renderer to load up the CPUs. In all cases, we asked SMPOV to use the same number of threads as there were CPU front ends in Task Manager—so four for the Pentium XE 840, two for the
Opteron 175, and so on.
The graphs below have results for "power management" and "no power management." That deserves some explanation. By "power management," we mean SpeedStep or Cool'n'Quiet. (In the case of the Pentium 4 600-series processors and the Pentium D 840 and Pentium XE 840 CPUs, the C1E halt state is always active, even in the "no power management" tests.) Sadly, the beta BIOS for our Asus A8N-SLI Deluxe mobo wouldn't support Cool'n'Quiet on the Athlon 64 X2 processors. AMD
says all of its dual-core chips will support power management once the proper BIOS support becomes available.
The Pentium D 820 doesn't support power management, as we've noted.
The AMD processors simply consume less power, both at idle and under load, than the Pentiums do. That's been the case for some time now, although Intel has made progress with Speedstep and the like.
Interestingly enough, the Pentium D 820's pair of 2.8GHz cores consume almost exactly as much power under load as the Pentium 4 670's single 3.8GHz core. This is one of the main reasons why Intel is moving away from higher clock speeds towards multi-core CPUs. We've already seen that the Pentium D 820 can often outperform the P4 670 in multithreaded applications, though they share the same basic power needs.
Overclocking Intel Pentium D 820
Test System Specs Processors: AMD Athlon64 X2 4400+ (overclocked up to 2.7GHz) Intel Pentium D 820 (overclocked up to 4.2GHz)
The Athlon 64 X2 4400+ is default clocked at 2.2GHz and features a 2MB L2 Cache, 1MB per core. The Pentium D 820 is clocked slightly higher at 2.8GHz and also features a 2MB L2 Cache.
The Athlon 64 X2 4400+ was overclocked to 2.7GHz (11x locked multiplier).
The Pentium D 820 was overclocked to an impressive frequency of 4.2GHz, using a 300MHz FSB (14x multiplier), making it 1.5GHz faster than the Athlon X2.
overclocking result
Conclusion of our review
I sure wish the Pentium D 820 supported lower multipliers for use with Speedstep, though. There's no good reason why this CPU should consume as much power at idle as it does.
he Pentium 4 670 is, I think, a good example of why the single-core approach wasn't working so well for Intel. Despite its high clock speed, the P4 670 struggles in some single-threaded applications, particularly games. The comparably priced Athlon 64 FX-55 is much faster, and so is the much cheaper Athlon 64 3500+. Multithreaded
apps do take advantage of Hyper-Threading and make the P4 670 more competitive—perhaps on par with the Athlon 64 FX-55 overall when multiple threads are in use. Even so, a Pentium 4 670-based system consumes about 45 more watts under load than an FX-55 system. Intel has managed to tame the Prescott core's heat and power needs somewhat through power management schemes and better manufacturing, but it's still rather hungry when going full tilt.
The Pentium D 820 typifies Intel's new approach, which looks very appealing given the numbers we've seen here today. In multithreaded applications, the Pentium D 820 races by the Athlon 64 3500+, which is a more expensive CPU. In fact, the Pentium D 820 frequently outperforms the Athlon 64 FX-55 and the Pentium 4 670, and our Pentium D system consumes no more power under load than our Pentium 4 670 rig.
Still, Pentium D 820's performance does present some rather bold contrasts. It's the slowest CPU in the pack whenever we throw a single-threaded test at it. The 820's gaming performance especially raises some red flags for us, as we've noted. Eventually, games will most likely make the conversion to multithreading, but in the interim, I worry that the newest, most intensive game engines may not run terribly well on a Pentium D at 2.8GHz. Many games will work just fine, no doubt, but those that use lots
of AI or physics may be a strain. Hard-core gamers will want to stay away, as will others who extensively use one single-threaded application at a time. The Athlon 64 3500+ is the better choice for them.
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