Intel's Pentium M on the Desktop - A Viable Alternative?
by Anand Lal Shimpi on February 7, 2005 4:00 PM EST- Posted in
- CPUs
Problem #2: Total Cost of Ownership
Intel has always kept desktop processors more affordable to ramp up production and reduce the cost of manufacturing while charging a premium on server and mobile processors; the Pentium M clearly falls into the latter category. Using our RealTime Pricing Engine (RTPE), we pulled the following prices for the Pentium M line at the time of publication:| CPU | Price |
| Intel Pentium M 765 (2.13GHz) | $645 |
| Intel Pentium M 755 (2.0GHz) | $435 |
| Intel Pentium M 745 (1.8GHz) | $299 |
| Intel Pentium M 735 (1.7GHz) | $245 |
| AMD Athlon 64 3500+ | $259 |
| Intel Pentium 4 560 (3.6GHz) | $430 |
The first thing to notice is that the flagship Pentium M processor is priced at $645, about the same as AMD's Athlon 64 4000+ clocked at 2.6GHz. The rest of the lineup is a bit more reasonable, but still fairly expensive. At $435, the 2.0GHz Pentium M 755 needs to be competitive with the 3.6GHz Pentium 4 560, and at $245, the Pentium M 735 needs to be able to hang with the Athlon 64 3500+.
The other pricey item for making the desktop Pentium M migration is the motherboard. Currently, only AOpen and DFI have motherboards available and, once again using our RTPE, both boards are priced at $230 - $240. That's over twice the price of desktop Athlon 64 and Pentium 4 motherboards; it's even more expensive than ASUS' nForce4 SLI based A8N-SLI Deluxe, which happens to be one of the most expensive desktop Athlon 64 motherboards.
Thankfully, memory and other components are identical regardless of whether you're building a Pentium M or a Pentium 4 system, but the price of the CPU and motherboard alone handicap the Pentium M from the start. But, if we can get beyond these issues of motherboard compatibility and price, is the Pentium M an attractive solution for the desktop?
To understand what the price premium buys you, it's easiest to look at a comparison of Thermal Design Power between the Pentium M and some of its desktop CPU competitors:
| CPU | TDP |
| Intel Pentium M 765 (2.13GHz) | 22W |
| Intel Pentium 4 520 (2.8GHz) | 84W |
| Intel Pentium 4 570 | 115W |
| AMD Athlon 64 | 67W |
Intel publishes a max TDP for their processors to aid their partners better in development of Intel based platforms, and using Intel's numbers, we see that the fastest Pentium M carries a 22W TDP, compared to the 84W TDP of the entry-level Pentium 4 520.
AMD publishes multiple TDP values for their processors based on the power states enabled by Cool 'n Quiet, the maximum of which happens to be 89W for the entire Athlon 64 line. Originally designed as a server chip, it's no surprise that the Athlon 64 is much more power-hungry than the Pentium M.
So, with the Pentium M, you get lower power consumption on the desktop, which arguably isn't as important as it is on the mobile side, but is still a neat feature to have - especially in the quest for a quiet-running PC.
But as we all know, a quiet, expensive Pentium M is useless if it doesn't perform up to par with the competition, so let's talk about performance a bit.
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bobsmith1492 - Monday, February 7, 2005 - link
Granted the T8000 here is an Intel fanboy, but please notice Anand was comparing clock-for-clock.T8000 - Monday, February 7, 2005 - link
There is one big difference between this review and the reviews where the Pentium M did very well: CLOCKSPEED!While others where able to get over 2.8 Ghz with aircooling, Anand got just 2.4 Ghz. This may be a coincidence, but it is the difference between surprisingly good performance and a few % below others.
As most of the benchmarks where based on the stock 2 Ghz, the difference became even greater.
So this review just shows that the stock speed Pentium M performs about 30% less with about 30% less clockspeed than overclocked versions.
A slightly redesigned version with higher voltages is not extremely unlikely to hit at least 3 Ghz. Combining that with a desktop chipset will result in stellar performance, as the benchmark scores in this review (x1.5) indicate.
But since there is no slightly redesigned version and Intel has no good reason to make one, the current Pentium M desktops will only appeal to overclockers and silent computing people.
Also, for some reason, Anand found the 90W TDP of the 2.4 Ghz A64 closer to the 20W of the P-M than to the 110W of the 3.8 Ghz P4.
CSMR - Monday, February 7, 2005 - link
That's a very good option Zebo, thanks for posting it.teutonicknight - Monday, February 7, 2005 - link
One suggestion: Why don't you start using a newer version of Premiere for testing? I personally don't use it, but every that I know who does says before Premiere Pro, the program sucked. I'm sure the render results would be much more realistic and accurate if you used a more up to date version of the programRegs - Monday, February 7, 2005 - link
I was wondering the same thing too Jeff. If you feed it more bandwidth, it would eliminate the pipeline stalls and maybe give it a chance to reach higher clock speeds. Right? Or is it still prohibited by the shorter pipeline to reach higher clock speeds?Longer pipeline = wasted clock cycles. But to me that sounds like the PM should actually scale a lot better with a speed boost. Why exactly does it scale badly compared to a P4? Could it be remedied in anyway with a dual channel memory bus?
ozzimark - Monday, February 7, 2005 - link
there's something wrong with the 3400+ in the spec tests. why is the 3000+ beating it consitantly?Warder45 - Monday, February 7, 2005 - link
Maybe I missed something but I don't see the reason for all the negitivity in the final words. The 2.4Ghz P-M was very close to the A64 2.4Ghz in many of the tests, 3D rendering seemed to slow it down but that looked like it. With better boards and memory the P-M might best the A64 in a clock for clock match up.I do agree the prices are way too high. I think Intel really needs to wake up and smell what they have cooking here. With more support and more aggressive priceing they could easily have a winner in the HTPC and SFF markets.
plewis00 - Monday, February 7, 2005 - link
Surely when someone builds a mainboard with the Sonoma (i915) platform using PCI-E and DDR2-533 then it will change. And I wouldn't have thought that's that far off assuming they don't charge rip-off prices for the technology. It would also be perfect for Shuttle systems where the emphasis is on quietness and coolness rather than so much on performance.Zebo - Monday, February 7, 2005 - link
CSMRSo's this one very soon..
http://www.xtremesystems.org/forums/showthread.php...
...more than excellent performance wise if Dothan is excellent...power differential hopefully for AMD will be nominal.
Sokaku - Monday, February 7, 2005 - link
While it is true that the A64 has way more bandwidth, I doubt that is the reason why it crushed the P-M in the Professional Applications. I think the real cause is to be found in the P-M's abillity to do FP divisions. The P-III had a pipelined FP unit, however div operations were extremly expensive. My guess would be that Intel haven't thrown much effort into improving on this.