Server duel: Xeon Woodcrest vs. Opteron Socket F

Power, prices, and conclusion

So far, we have concentrated on processor performance, but these days, one hears the expression 'performance per watt' quite a lot. We have examined four complete server systems during the running of the benchmarks to see how much power they consumed under load. We are not talking about absolute maximums here, but rather the consumption under a realistic sort of pressure. Since we only had a separate motherboard available for the Socket F Opteron (instead of a complete server as was the case for the other processors), we have not taken it into consideration here. Instead, we assume that the Socket 940 version should give a fair picture of how AMD servers generally perform in the energy realm. Presumably, the Socket F version will need less power due to the use of DDR2 memory, but that advantage will partially evaporate due to the fact that its performance is slightly less. The performances per Watt have been obtained by looking at the average number of pageviews per ten minutes under a load of 25 to 100 users, and dividing this by the amount of Watts measured.

	Absorbed power under load
	Primergy RX300 S3 (Dempsey)	447
	Fire X4200 (Opteron (DDR))	341
	Primergy RX300 S3 (Woodcrest)	294
	Fire T2000 (UltraSparc T1)	232

Performance/Watt	MySQL 4.1.20	MySQL 5.0.20a	PostgreSQL 8.2-dev
Woodcrest	685	740	1004
Opteron (DDR)	527	524	644
Dempsey	325	344	592
UltraSparc T1	397	233	766

	Average performance
	Woodcrest	238032
	Opteron (DDR)	192740
	Dempsey	187924
	Opteron (DDR2)	181939
	UltraSparc T1	108010

	Average performance per Watt
	Woodcrest	810
	Opteron (DDR)	565
	UltraSparc T1	465
	Dempsey	420

On average, the new Xeon offers the best performance per Watt: it is almost 93% more than the Netburst-based Dempsey, 43% more than the AMD Opteron, and 74% more than the Sun UltraSparc T1. Although these figures are not representative for all the various servers and applications, we can conclude hat Woodcrest is quite an efficient chip, which seems to be hardly bothered by its external memory controller and warmer FB-DIMM modules at the system level. The average performance gains of 23% to 31% above the competition further add to the good impression that the CPU makes. Another significant factor is the price of the processors. Even though this is only a small part of the total cost of a server, the pricelist nevertheless gives a good indication of the processors' various positioning:

Socket F Opteron			Woodcrest			Dempsey
						3.0GHz (95W)	$177
			1.66GHz (65W)	$209
1.8GHz (95W)	$255		1.86GHz (65W)	$256
1.8GHz (68W)	$316		2.0GHz (65W)	$316		3.2GHz (130W)	$316
2.0GHz (95W)	$377					3.2GHz (95W)	$369
2.0GHz (68W)	$450		2.33GHz (65W)	$455
2.2GHz (95W)	$523
2.2GHz (68W)	$611
2.4GHz (95W)	$698		2.66GHz (65W)	$690
2.4GHz (68W)	$768
2.6GHz (95W)	$873		3.0GHz (80W)	$851		3.73GHz (130W)	$851
2.8GHz (120W)	$1165

Here, too, things do not look too bright for AMD. For every Opteron one can find a similarly or lower priced Woodcrest, that is faster and/or more energy efficient. In these tests, we did not consider the top models, but it is not the case that one brand has more headroom than another. For instance, going up a step on the price ladder makes the difference in clock speed 400MHz as opposed to 266MHz. The 'special edition' Opteron at 2,8GHz approaches the top model Woodcrest, but it is 314 dollars more expensive and comes with higher power consumption as an extra bonus.

Beside the processor price, the cost of memory is of course also important. Since FB-DIMM requires an extra component (the buffer chip), it is expected to be more expensive than ordinary DIMM at the same clock speed. In other words, the choice for Woodcrest implies extra 'hidden' costs. However, it is difficult to determine exactly how big the difference is. Our Pricewatch section lists 1GB DDR2-667 from about 100 euros, while the equivalent FB-DIMM is priced at almost 160 euros. That keeps the Opteron interesting for those who want to assemble their own machines and want plenty of memory at little cost. But those who do business with one of the large manufacturers see a different picture. Well-known brands ask exorbitant prices for memory, whether it is DDR(2) or FB-DIMM does not make an awful lot of difference. At IBM, however, the only large manufacturer at the time of publication that sells both DDR2-667 and FB-DIMM, the buffered version is a little cheaper. Dell, too, offers a fair deal on FB-DIMM in relation to DDR2-667-modules from IBM and Sun.

Prices of 1GB memory
Manufacturer	Registered DIMM	FB-DIMM (667MHz)	Difference
Dell	$190 (DDR2-400)	$228.50	20.3%
IBM	$255 (DDR2-667)	$249	2.4%
HP	$254.50 (DDR400)	$274.50	7.9%
Apple	$315 (DDR2-533)	$350	11.1%
Sun	$247.50 (DDR2-667)	-	-

The introduction of Blackford and Woodcrest allows Intel some breathing space for the time being. At last the Opteron has a more than worthy competitor, that outperforms it in terms of performance, power efficiency, and price. AMD can consider itself lucky that Intel's new architecture is not suitable for four sockets at the moment – the market segment where AMD's gains have been most significant – since in the other areas Intel's main competitor appears to have been taken completely by surprise. The fact that there is no immediate answer from AMD does not mean that the battle is over. Both companies are working hard on the development of quadcores. Intel aims to release its 'Clovertown' within a few months and AMD is due to release a four core CPU mid-2007.

AMD is also working on an improved K8 version under the codename K8L. As far as is currently known, this will not introduce many radical new features as in the Core architecture, but it does share certain important characteristics with Core, such as 128 bit broad multimedia Units. However, according to the latest gossip, the K8L design will not be entering the field until the beginning of 2008. That would mean that the first quadcore server chips will be based on the current K8 design.

We hope to find out soon if Core is strong enough to stay ahead over the next few years. Woodcrest appears to be rock-solid, but the disappointing scaling characteristics may cause Intel problems switching to quadcores and four socket systems. Even if that goes smoothly AMD might pull a rabbit out of its hat in the form of K8L. So, the future is hardly carved in stone, but for now the choice for us was easy: in part on the basis of these benchmarks we have ordered a dual 3GHz Woodcrest server for our forum database.

Acknowledgements

Tweakers.net wishes to thank Fujitsu-Siemens (Woodcrest en Dempsey), MSI (Socket F motherboard), Adata (DDR2 memory), Sun (Socket 940 Opteron and UltraSparc T1), AMD, and Intel for their cooperation to this article. Also, we want to thank Mick de Neeve for the English translation and once again ACM and moto-moi for executing the benchmarks and giving valuable information which aided the interpretation and the description of the results.

Previous articles in this series

30-7-2006: AMD Socket F
27-7-2006: Sun UltraSparc T1 vs. AMD Opteron (Dutch)
19-4-2006: Xeon vs. Opteron, single- en dualcore (Dutch)