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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fitten - Tuesday, February 8, 2005 - link
Also, it's interesting that there are many benchmarks chosen which are known to stress the weaknesses of the Pentium-M... not that it isn't interesting information. For example, there seems to be a whole lot of FPU intensive benchmarks (around 15 or so, all of which the Pentium-M should lose handily - known before they are even run) so kind of just hammering the point home I guess.Anyway, the Dothans held up pretty well from what I can see... Most of the time (except for the notable FPU intensive and memory bandwidth intensive benchmarks), the Dothan compares quite well with Athlon64s of the same clock speed that have the advantage of dual channel memory.
fitten - Tuesday, February 8, 2005 - link
The other interesting thing about the Athlon64 vs. Dothan comparison is that even with dual channel memory bandwidth on the Athlon64's side, the single channel memory bandwidth of the Dothan still keeps it very close in many of the benchmarks and can even beat the dual channel Athlon64s at 400MHz higher clock in some.Anyway, the Pentium-M family is a good start. Some tweaking here and there (improved FPU with better FPU performance and maybe another FPU execution unit, improved memory subsystem to make good use of dual channel) and it will be at least as good as the Athlon64s across the board.
I own three Athlon64 desktops, two AthlonXP desktops, and two Pentium-M laptops and the laptops are by no means "slow" at doing work.
KristopherKubicki - Tuesday, February 8, 2005 - link
teutonicknight: We purposely don't change our test platform too often. Even though we are using a slightly older version of Premiere, it is the same version we have used in our other processor analyses.Hope that helps,
Kristopher
kmmatney - Tuesday, February 8, 2005 - link
There's also a Celeron version that would have been intersting to review. The small L2 cache should hurt the performance, though. I think the celeron version using something like 7 Watts. It would make no sense to put a celeron-M in such an expensive motherboard, though.Slaimus - Tuesday, February 8, 2005 - link
I think this indirectly shows how AMD needs to update its caching architecture on the K8. They basically carried over the K7 caches, which is just too slow when paired with its memory controller. Instead of being as large as possible (as evidenced by the exclusive caches) at the expense of latency, the K8 needs faster caches. The memory bandwith of L2 vs system memory is only about 2 to 1 on the K8, which is to say the L2 cache is not helping the system memory much.sandorski - Monday, February 7, 2005 - link
I think the Pentium M mythos can now be laid to rest.mjz5 - Monday, February 7, 2005 - link
to #29:your 2800 is the 754 pin.
the 3000+ reviewed is the 939 pin which is 1.8. the 3000+ for the 754 is 2.0 ghz
kristof007 - Monday, February 7, 2005 - link
I don't know if anyone else noticed but the charts are a bit off. My A64 2800+ is running at a stock 1.8 ghz .. while in the review the A64 3000+ is running at 1.8 ... weird!knitecrow - Monday, February 7, 2005 - link
#251) Intel and AMD measure TDP differently... and TDP is not the same as actual power dissipation. The actual dissipation of 90nm A64 is pretty darn good.
2) A microprocessor is not made of Lego... you can't rearrange/tweak parts to make it faster. It takes a lot of time, energy and talent to make changes -- even then it may not work for the best. Prescott anyone?
Frankly I’ve been waiting for a good review of P-M's actual performance. I really don't trust those "other" sites.
k00kie - Monday, February 7, 2005 - link