Benefits of 2x1 Mb cache over 2x512?

pepsimax2k

Member
Jan 23, 2004
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Hi, could anyone tell me what real world benefits there may be getting a dual core processor with 2x1Mb L2 cache as opposed to a similar clocked processor with 2x512Mb L2 cache?

I've had my eye on a 65w 4000+ windsor core (clocked @ 2.0 Ghz, 2x1Mb) that beats a 65w 4000+ brisbane core (clocked @ 2100GHz, 2x512Kb) on most benchmarks. Problem is, they're not so readily available anymore, and I'm wondering if I should really care about the 2x1Mb cache.

So I just spent ages comparing cpus and tallying things up on tom's cpu benchmark chart @ http://www23.tomshardware.com/cpu_2007.html

contenders were an e2140, e2160, 4000+ x2 windsor (2000 + 2x1), 4000+ x2 brisbane (2100 + 2x512), and 4200+ x2 brisbane (2200 + 2x512). they're all similarly priced @ around £35 to £40 on ebay, although the e2160 is the most expensice, as is the windsor 4000+ due to availability.

what I found was (and this is based on the number of benchmarks they were faster than the another cpu in, plus a bit of intelligence interpreting scores),

4200+ brisbane > e2160 (by a bit) and 4000+ windsor (kills it)
e2160 > 4000+ brisbane (not by too much)
4000+ windsor > 4000+ brisbane (by v v little, and real world progs) and e2140 (kills it)
4000+ brisbane > e2140

the fact the 1 Mb cache 4000+ beat the 512 Kb cache version by so little (basically, 1 bench mark between em, and 1Mb version won more real world prog tests) suggests there's very little difference in performance to gain by the larger cache, at least at those clock speeds. and when a slightly higher clock is involved, it takes presedence over cache amount and +200GHz gives a much better cpu even with -50% cache.


what i'm wondering is, am i missing anything? is there actually anything to gain for the larger cache size, and should i hold out to get the 4000+ windsor chip over either the brisbane version or 4200+ ?


oh and, this is ignoring all overclocking abilities. obviously the intels are gonna beat everything there, although... how oc'able is the 4200+ x2?
 

Denithor

Diamond Member
Apr 11, 2004
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I presume that you are focused on AMD chips because you already have a s939 or AM2 motherboard and want to upgrade by just dropping in a faster chip? If so, check out the table at the top of this page to see how much impact 2x1MB has versus 2x512KB (short answer: not much except in games).

You are definitely correct in one thing there: the overclocking factor makes choosing to build an AMD system from scratch kinda silly right now.

If you are considering the 1MB/2MB/4MB C2D chips, take a look at the A/V encoding comparisons here and the gaming results here. Basically, an e2160 @ 3.2GHz matches or beats a stock e6850 in most cases. And then consider that the e6850 will easily beat even the X2 6400+ and you really have an answer to which series to choose from.
 

pepsimax2k

Member
Jan 23, 2004
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thanks for that link.

yeah, i was focusing on amd chips; as i can get a 4200+ cheaper than a 2160, and its considerably faster in benchmarks i've seen, and the am2 board is gonna end up much cheaper... though i'm actually building from scratch so have my choice of parts so long as the price is right.

and as for ocing, if it was me i'd almost certainly get an intel chip, but given that a) i've only ever oc'd two chips, and one of those died after a single 2 MHz fsb change too far, i don't think my 50% failure rate is gonna instil much confidence in anyone... and b) the system's not for me. which would make it twice as bad if i messed anything up. and logevity/stability is key so frankly anything clocked too far from defaults is off limits :( i may convince the owner to let me up it a couple Ghz after a couple years, but i wouldn't wanna go much further than that anyway so it makes little difference what chip i use.

one day i shall have my own money to spend though... or get a full time job building other's systems... you don't know any decent vacancies in the uk do you? yorkshire area? i got a 50% success rate in ocing and a stubborn streak to make anything work?
 

Pyrokinetic

Senior member
Dec 4, 2005
296
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As for the overclocking part, the only real way to kill a chip is through adding voltage, so it is wise to pay attention to other's limits in such an area.

Most AMD X2 chips can hit 2.7Ghz (as my 3800+) and will be even easier with the higher multipliers of the 4000+ and the 4200+. Anandtech noted that some of the later batches of the 3800+ chips can hit 3.0Ghz or higher http://www.anandtech.com/mb/showdoc.aspx?i=3051&p=2 unfortunately, my own chip was not one of those.

My chip would boot at 2.8Ghz, but one core just could not pass extended Prime95 stability testingat that frequency. My system is currently set at 302 x 9 (2.718Ghz).

As for voltage, 1.45V for the X2s is quite safe: http://forums.anandtech.com/me...yword1=quick+and+dirty though I personally have used up to 1.65V on my X2 without issue, and it currently set at 1.55V. I would be hesitant to go over 1.65V though.
 

Blain

Lifer
Oct 9, 1999
23,643
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> Tom's comparison to find out, "Does Cache Size Really Boost Performance?" <
(Processors used... E2160 @ 2.4GHz, E4400 @ 2.4GHz, X6800 @ 2.4GHz)

* Games = Yes, you'd get a few extra FPS.
* File compression = Yes, you'd save a little time.
* Rendering = No, save your $$.
* Transcoding = Audio, no. Video, you'd save very little time with more cache.
* Synthetics = Of course you'd see a difference, but still not much.
 

tvdang7

Platinum Member
Jun 4, 2005
2,242
5
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look at the AT halflife episode 2 performance. the 1mb kill t he 512kb amd cpu's and same for intel
 

BitByBit

Senior member
Jan 2, 2005
474
2
81
As alluded to, real world application performance show a slight benefit, which is usually easily overcome by a 200MHz clock speed increment by an equivalent 512KB core. Having said that, I was surprised to notice an unquestionable increase in general responsiveness when I upgraded to a 5600+ from a 4200+. This cannot be attributed to the clock speed advantage of the former, since Cool n Quiet clocks both at 1.0GHz under light usage. Take that as you will.
 

taltamir

Lifer
Mar 21, 2004
13,576
6
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well bigbybit, thats the whole POINT of a bigger cache... bigger cache means more buffer means less WASTAGE of cpu cycles... just because your CPU isn't at 100% load doesn't mean it can't be faster... The exact same cpu design with more cache means you will be at a HIGHER load actually while doing the same thing, and getting better speed.. In fact, in 100% load you will not see a difference due to cache..

If CPU A and CPU B are completely identical except that CPU B has twice the cache...
Example 1 - Running seti at home / video encoder, a super small sequential application with tons of data calculation.
CPU A: 100% usage - 100 hypothetical speed units.
CPU B: 100% usage - 100 hypothetical speed units.

Example 2 - You are trying to run a CPU intensive program / game that is acting very slow but you are not at 100% cpu usage.
CPU A: 60% usage - takens X seconds to perform the operation
CPU B: 80% usage - takes less time to perform the operation then cpu A.

Thats why extra cache makes the computer faster. It makes the CPU get closer to 100% utilization on programs that are limited by cpu speed but simply cannot get the data to the cpu fast enough.

AMD has traditionally been focusing on very very small caches but very fast transmission... while intel has been focusing on slower transmission but with massive cache... thats why intel gets more of a benefit from a bigger cache.
 

BitByBit

Senior member
Jan 2, 2005
474
2
81
I'm sorry, but that is the worst explanation of how cache helps performance I've ever read on here. In application performance, additional cache is equivalent to a frequency increment. Both result in an equivalent task consuming less CPU resources than a slower/cache thrift processor. The reason I was surprised to note an increase in general responsiveness is because cache improves the performance of a particular application, and generally not in switching between tasks, where I noticed the boost.
 

RussianSensation

Elite Member
Sep 5, 2003
19,458
765
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Originally posted by: pepsimax2k

4200+ brisbane > e2160 (by a bit) and 4000+ windsor (kills it)

This will depend on the application. In games for example E2140 1.6ghz outperforms X2 3800+ 2.0ghz - Benches

For less than $10 you can go up to E2180 2.0ghz from 2160.

Also don't forget:

1) Just by increasing the FSB to 333 (FSB 1333 effective) on any P35 board like $95 DS3L you are looking at 3.33ghz overclock on the E2180 without overclocking the motherboard or ram. Overclocking has never been easier than this other than upping the FSB on an XP2500+ from 166 to 200....ah the memories. But like you said if overclocking isnt for you then consider advantage #2 below.

2) You have full upgrade path to quads on G0 steppings and Penryn which both overclock better and outperform Phenoms at stock settings.

Performance with Penryn is clear while there is little certainty this time how fast Phenom will get over its life. However, a 4.2+ghz 45nm Penryn Quad as a cheap upgrade in 2 years is looking good :)