Xeon L5520 - the next ultimate low-ish power CPU?

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shleepy
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Xeon L5520 - the next ultimate low-ish power CPU?

Post by shleepy » Mon Mar 09, 2009 3:13 pm

Do a quick search on Google, and you shall find a shortly upcoming Intel CPU - Xeon L5520. This is a 2.26GHz, quad-core (+ hyperthreading to make a total of 8 virtual CPU's), 8Mb L3, 60W CPU. The interesting part is the last number - 60W. This makes it the lowest-power i7 yet.

But to me, those numbers are a little questionable. The popular i7 920 CPU, currently the cheapest i7, is 130W and 2.66Ghz, but otherwise has the same specs. How much difference would the lower clock speed make? Intel likes to make users play guessing games, it seems to me, as to whether the CPU will really use a similar amount of energy as the TDP, or significantly less. So, in theory, that 60W could really be 35W at load, if it's something like the E8x00 series. But more importantly, I'm wondering if 2.26GHz is really enough to give it a boost over the low-power current generation 771 or 775 offerings (e.g., L5420 or Q9400S), which have much higher frequencies. Will the brilliant Nehalem architecture be enough?

And while we're at it - there are 80W and 95W Xeons that will be coming out soon... Again, similar specs to the 920, but actually faster and lower-powered. Can we expect some of them (or maybe the mainstream, non-Xeon i7's) to be fairly low power in the very near future?

Anyway, I'm just theorizing... anyone have some thoughts?

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Post by Blue_Sky » Mon Mar 09, 2009 6:30 pm

I've always thought that the L5420 would make for an awesome build. The L5520 seems to be its replacement, at a TDP of only 10 W higher. I hadn't heard of the processor before you mentioned it, but my curiosity has been piqued. 60W is less than half of a i7 9x0, but Xeons have always had much more interesting specs, so I'm going to refrain from speculating and wait for a test or two.

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Re: Xeon L5520 - the next ultimate low-ish power CPU?

Post by jessekopelman » Tue Mar 10, 2009 7:15 am

shleepy wrote:How much difference would the lower clock speed make?
The real issue is not the clock speed in and of itself but the voltage this part is spec'd for. Also keep in mind that one reason for the i7 super-high listed TDP is their ability to auto-overclock (aka turbo). I'm pretty sure they could have been spec'd at 95W or even lower if not for that feature. Perhaps the L5520 has no turbo feature?

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Post by austinbike » Mon Mar 23, 2009 2:21 am

That is one of the biggest issue in the xeon line is the inconsistency of features.

As you move from the top of the stack to the middle and the middle to the bottom, features get cut, memory support gets cut, cache gets cut, features get cut.

At least with opteron the features are consistent across all of the processors in the family.

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Post by FuturePastNow » Mon Mar 23, 2009 4:47 pm

TDP is not the exact power consumption / heat output of the processor. It's more like it defines a maximum range, and with binning of better parts, I have no trouble understanding how Intel could classify a Nehalem CPU as 60W.

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Post by smilingcrow » Tue Mar 24, 2009 3:47 pm

FuturePastNow wrote:TDP is not the exact power consumption / heat output of the processor. It's more like it defines a maximum range, and with binning of better parts, I have no trouble understanding how Intel could classify a Nehalem CPU as 60W.
Xeon Nehalem DP is released next week so it will be interesting to read the reviews to see the real world figures.

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Post by austinbike » Sat Mar 28, 2009 1:30 pm

Keep in mind that LV DDR-3 isn't available until next year. DDR-3 eats up ~1W per DIMM over DDR-2. If you are running triple channel that is more DIMMs and more heat. Plus the latencies are pretty high, CL=7/CL=9. Q1 or Q2 2010 DDR-3 gets a lot better

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Post by edh » Sat Mar 28, 2009 1:52 pm

Just some calculations:

Just on frequency:
130 x 2.26/2.66 = 110W

Assuming V is proportional to f:
110 x (2.26/2.66)^2 = 80W

Still not 60W.

Even so, the i7 920 will not be 130W. That's merely the bracket it's been put in, the same as the 940! The Xeon may actually be a real power rating as it's a processor for grown ups.

Using the model of the 940 the TDP would be 59.65W. Not far off.

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Post by smilingcrow » Sat Mar 28, 2009 2:43 pm

From a Nehalem Mac Pro Review – Macperformance Guide:

“Power usage is amazingly good for this class machine. Past Mac Pros would hit the 550 watt range under full load; the MP09 maxes out at about 350 watts under the most severe load.
Stock config takes 138 watts idle (single drive spinning).
With 4 drives and 16G, when the drives spin down the MP09 takes only 136 watts.
About 5 watts more for 16GB vs 6GB.
Up to 325 watts under full compute load (all 16 cores busy) with 16GB and single drive. Add another 20 watts or so four 1TB drives.
With 16GB and 4 drives (+SSD), under full stress 350 watts.â€

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Re: Xeon L5520 - the next ultimate low-ish power CPU?

Post by merlin » Tue Mar 31, 2009 2:30 pm

The Xeon L5508 is a bit more crazy. 38w at 2ghz! Unfortunately it's not really for general consumption, it's specific for embedded communications needs, but I'd think that's the ultimate low power cpu. But more realistically, I agree the L5520 looks really good for a low power, high speed quad core.

Hmm, well change that, the L5508 is actually dual core. Impossible to tell without seeing the embedded device specifications page.
Last edited by merlin on Tue Mar 31, 2009 3:39 pm, edited 1 time in total.

shleepy
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Post by shleepy » Tue Mar 31, 2009 2:43 pm

By the way, I noticed that these are finally in stock in the US... cheapest price is from eBay stores for $570, shipped, I think (and -14% with live cashback). Search for BX80602L5520, if you're interested.

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Post by smilingcrow » Tue Mar 31, 2009 3:03 pm

Take a look at the review at Anandtech. They are staggeringly good for Server loads, almost unbelievably so, I’ve never seen anything trump the competition so comprehensively.

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Post by Blue_Sky » Tue Mar 31, 2009 3:55 pm

The Xeon L5508 is a bit more crazy. 38w at 2ghz! Unfortunately it's not really for general consumption, it's specific for embedded communications needs, but I'd think that's the ultimate low power cpu. But more realistically, I agree the L5520 looks really good for a low power, high speed quad core.

Hmm, well change that, the L5508 is actually dual core. Impossible to tell without seeing the embedded device specifications page.
I'm curious about those numbers. As a generalization, Bloomfield is supposed to be 20% faster, clock for clock than Wolfdale. An E8400 is supposed to draw ~35W maximum. Does that then mean that the L5508 is actually less computing power per watt than the last generation? Or is there some hyperthreading magic that occurs?

I hope we get a review soon.

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Re: Xeon L5520 - the next ultimate low-ish power CPU?

Post by smilingcrow » Tue Mar 31, 2009 7:27 pm

merlin wrote:The Xeon L5508 is a bit more crazy. 38w at 2ghz!
But it's only dual core so it's not a big deal really.
Blue_Sky wrote:I'm curious about those numbers. As a generalization, Bloomfield is supposed to be 20% faster, clock for clock than Wolfdale. An E8400 is supposed to draw ~35W maximum. Does that then mean that the L5508 is actually less computing power per watt than the last generation? Or is there some hyperthreading magic that occurs?.
An E8400 has a TDP of 65W versus 38W for the L5508. Comparing the TDP of one CPU with the ‘supposed draw’ of another chip isn’t going to give you particularly meaningful data.
The L5508 also supports Turbo Boost just to muddy the waters even further so may top out at 2.26GHz or higher.

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Post by Blue_Sky » Tue Mar 31, 2009 8:26 pm

Oops, completely missed that. Thought it had a 60W TDP like the rest of the 550x CPUs. I guess that my earlier question is moot them. I doubt that 35W is just supposed. I've seen some reasonably vigorous investigations pegging it between 32 and 35 W for an E8500.

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Post by smilingcrow » Wed Apr 01, 2009 6:57 am

Blue_Sky wrote:An E8400 is supposed to draw ~35W maximum.
smilingcrow wrote:Comparing the TDP of one CPU with the ‘supposed draw’ of another chip isn’t going to give you particularly meaningful data.
Blue_Sky wrote:I doubt that 35W is just supposed. I've seen some reasonably vigorous investigations pegging it between 32 and 35 W for an E8500.
I was only quoting you. :)
But my point is that comparing the measured power draw of one CPU with the TDP of another doesn't seem meaningful anyway.

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Post by Blue_Sky » Wed Apr 01, 2009 8:27 am

I wasn't using supposed in that sense, but there is no way of conveying that in text. I should have used another word. I was referring to the TDP/draw comparison above - I think we have all realize that Intel's TDPs aren't that useful, except to establish some sort of power draw hierarchy.

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Post by austinbike » Wed Apr 01, 2009 4:57 pm

smilingcrow wrote:Take a look at the review at Anandtech. They are staggeringly good for Server loads, almost unbelievably so, I’ve never seen anything trump the competition so comprehensively.
Hmmm. Not so sure about that. If you go to Dell's site and price out a 2P 2.7GHz opteron system and a 2.93GHz xeon system, apples to apples, the xeon is ~100% more expensive.

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Post by smilingcrow » Wed Apr 01, 2009 5:30 pm

austinbike wrote:If you go to Dell's site and price out a 2P 2.7GHz opteron system and a 2.93GHz xeon system, apples to apples, the xeon is ~100% more expensive.
But to match the performance you’d need two of the Opteron systems which would have roughly twice the running costs (power, cooling, maintenance contracts) and that’s not including the extra software licensing costs of running two machines.
Or you could buy an Opteron quad processor system and enjoy the price tag on that.

But that’s only one way of looking at it and it’s really not as simple as that and certainly not as simple as just speccing two machines on Dell’s website. :o
Every server installation is unique and there are many variables that need to be taken into account when choosing the appropriate hardware, software and ancillary items. For low to mid range 2P solutions I’m sure AMD will still be very competitive.

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Post by merlin » Thu Apr 02, 2009 11:28 am

Also if you're going to compare, you shouldn't be using the Xeon 5500 series yet. These are brand new and currently priced without discounts unlike the Opterons. If anything, price comparisons should be made against the 5400 series.
Also the TDP and TCO of the xeon 5500 series will probably be much better than opterons. Equal power usage, much higher performance = win for costs and power usage in the long run. If you're going to compare costs, compare the total package, not the initial buy.

And personally if I were building a serious server, there's no way I'd skip a Xeon 5500 series now. It's the only thing that makes sense imho unless you somehow can't afford the initial cost at all.

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