Fastest CPU for SETI?

[Ben98SentraSE]

Dunno if/when the last time this has been discussed but I'm asking again

I know SETI is FPU dependent. My K62-350 and P266MMX are pretty close in WU times, the P233MMX actually makes more MFLOPS in this CPU test proggie I have.

Seems that the best budget system in general is a Duron 600 overclocked to 900 or 950 with say an Anandtech approved ABIT KT7. How much faster would an equally clocked Thunderbird be? Or a nicely overclocked Celeron to 850 on a nice BX133 board? Or is the PIII king of SETI? I've read SETI likes large caches too.

What's the scoop?

 

[Michael]

Ben -

First, nice jump back into the SETI hunt!

The older clients really, really benefit from a large cache, PC100 ram and low multipliers. So Xeons and Pentium III's (around 500/550) offer great SETI scores.

Michael

 

[Ben98SentraSE]

I'm confused.. so a PII-800 wouldn't be better?

And why do we care about the older clients? You mean GUI 2.04?

More confused now...

 

[Ken g6]

Yes, I think if you could overclock a Xeon a lot, that would be good. Seti doesn't fit in a cache smaller than 528k. Also, I hear Ultra Sparcs are very good at SETI, if you can afford them.

Oh, but that could all change with version 3.0!

 

[Michael]

In total efficiency, chips with larger cache and lower multipliers on a 100 FSB give the most bang per Mhz. Yes, a P3 800 is faster than a P3 500, but the P3 500 may give more bang for the buck.

Yes, older means the 2.04. 2.7x betas are less dependent on cache.

Michael

 

[Ben98SentraSE]

So in order, what's better? (clock speed obviously, you can leave that out)

Cache size?
Cache speed?
PIII current core? (forgive me for forgetting the codename)
Thunderbird core?

That's the ultimate SETI speed speed discussion. How about bang for the buck? Would the Duron 600 overclocked to 900 or 950 be an excellent choice? Or a lower end PIII? Celeron? Low end T-bird or K75 core Athlon?

 

[ElFenix]

cache size, has to be bigger than 512k for seti to fit its code and the wu, is most important, currently. assuming that cache is too small the next most important factor is fsb. a 133mhz fsh performs significantly faster than a 100 mhz fsb. just an illustration, i have a p3 700 that does a wu in about 7:30, while i have a p2 400 that does one in about 8:30. so only 1 hour less, about 13%, for 75% more mhz. this is because the fsb and memory bandwidth are saturated at 500 mhz. moving to an athlon with a 200mhz fsb doesn't really fix the problem because it is still limited by its memory bandwidth. ideally you would find a processor that is easily overclocked to 150mhz fsb/memory, i'm thinking p3 667s and 800s are candidates.

celeron is suck, cuz even if you oc it to 850 the fsb is still 100mhz, which is choked at 500mhz.

 

[Ben98SentraSE]

FPU seems to be a big factor too maybe moreso than FSB cuz my P266MMX is running at 75MHz FSB and the K62-350 is running at 100MHz FSB (and won't overclock to save it's life), yet they are REALLY close in WU speed.

So how bout AMD vs. Intel for SETI?

 

[networkman]

SetiSPY, a 3rd party utility to monitor the Seti client(very useful with the cmd-line version) lists the following info for the relationship between processors/L2cache and SETI speed, with the fastest being at the top:

CPU {L2 Cache}
----------------------------------------
HP PA-RISC 8600 {1.5 meg}
Intel PIII Xeon(model A) {1 or 2 meg}
Intel PII/PIII Xeon {1 or 2 meg}
PowerPC MPC7400(G4) {1 meg}
PowerPC 750(G3) {1 meg}
Sun UltraSPARC IIi {256k}
Intel PIII(Coppermine) {256k}
Intel PII/III {512k}
Intel Celeron {128k}
AMD Athlon {512k}
Intel Pentium Pro {256k}
AMD K6-III {256k}
Intel Pentium {512k}
Cyrix MII 6x86 {512k}
Intel Celeron II(Coppermine128) {128k}
AMD K6-2 {512k}

As has been discussed at length in some other forums, the SETI client performs optimally in an L2 cache of greater than 512k, as the Xeon CPUs can have; however, having greater than 1 meg of L2 cache will generally give no better performance, so a 2meg PIII Xeon will generally perform no better than it's 1meg brother. And for those of us that have to be concerned with price versus performance, saving money by getting the 1meg Xeon can be VERY helpful.

Also, while L2 cache is important, a greater bus speed than 100 can be as much or more of a factor when considering which processor to purchase. And don't forget the multiplier factor that ElFenix has done such a good job of pointing out! A P3-800(100FSB) may not perform much better than a P3-550(100FSB), due to saturation of the bus and memory bandwidth.

Reading through other threads, you may find people claiming to do SETI work units in under 4 hours! While some work units can be noisy, and thus quickly completed/discarded, many times you'll find that the user has over-clocked the processor to speeds greater than a 133FSB! In fact, some people have over-clocked their processors and memory to as high as a 150FSB(and even higher!) With this kind of memory bandwidth, performance can soar!

 

[Ben98SentraSE]

AHA! The P266MMX has an FIC PA-2007 mobo with 1MB of external cache! And I'm sure the K62-350 mobo doesn't have that much. So maybe what I thought of an FPU ability issue is really an L2 cache size issue.

So CPU cores aren't nearly as dependent as L2 cache size it and overall memory bandwidth? So the new DDR SDRAM would probably do really good

So PIIIs are really the only things that can get to 150MHz bus speed? Can Athlons get there? I mean would my purchase idea of a Duron 600 to 900 or 950 wouldn't do much unless I increased the bus speed a lot?

What would ya'll buy for a new system for little money to do good at Seti? Best bang for the buck?

 

[TuffGuy]

my system finishes seti packets in 3-4hours. i'm running at 143mhz cas 2-2-2.

athlons/t-birds/durons can only get to about 110mhz fsb due to the ev6. your best bet would be to get a p3-500/550 and overclock it i think... or to get a dual processor board and run two separate instances of seti under win2k. it will not speed up the individual unit, but you can process 2 at the same time.

 

[zzzz]

If you wait for few days, the new client is less cache dependant. My duron 600@900 times almost halved when I downloaded the beta...
the 2.76 beta..
before I had 8.3 hours per WU. now its like 4.5 to 5 hours!

 

[TuffGuy]

zzzz - which version it it most similar to?

 

[Ben98SentraSE]

You mean this client?
http://forums.anandtech.com/messageview.cfm?catid=39&threadid=236715

Or something else?

 

[JWMiddleton]

Hi Ben98SentraSE,

I figure I'll throw in my 2cents worth. I spent a bunch of time yesterday playing with a PIII-450 that I can overclock to 568 MHz. As I increased the FSB I noticed that the speed and efficiency was going down rather than increasing (the L2 Cache Latency was being increased.) At 568 MHZ, the time to finish a WU was over 9 hours. By reducing the speed back to 450 MHz and changing a few BIOS settings I got that number down to 7.75 hours. (cli 2.04) I have a Cel300A/450 that runs a WU in about 8.5 hours and a PIII-550e/733 running a WU in 5.5 hours. Both do so with no tweaking. The best time I've been able to get is with a PIII-700/910 on a ASUS CUSL2 mobo at 4.4 hours. There is a lot of good tweaking info over at ARS-Technica (booooo-bad team-just look, don't stay!). The above basically agrees with Michael that you reach a point of diminishing return with the speed of the CPU.

TuffGuy was correct in that getting the BESTPC133 memory that is CAS2 (CL2, 222) compliant to run with a PIII CU that will give you the highest FSB will give the fastest results. To go with this you need a chipset that will take advantage of both, such as the i815e or BX chipsets.

Good Luck

 

[Michael]

The amazing thing about the list is how low the CII's are. I'm definately going to upgrade my main machine to a P III 800.

John (JW) - just to make you worried, someone has offered to throw &quot;A few dozen PA-8X00 with several dozen Gigabytes of memory&quot; behind my efforts for a little while <big grin>.



Heavy Metal

Michael

 

[Michael]

My first double post ever!

Michael

 

[xtreme2k]

i think a 550E overclocked to 825/150 will KICK in seti, due to the bus

other than that, the xeons 1MB will also shines

 

[JWMiddleton]

Michael: Intel added latency to the L2 cache of the CelII, so that an overclocked CelII-533 to 800 will not compete with the PIII-800e as the Cel300A/450 did with the PII-450.

 

[TuffGuy]

xtreme2k - do you know how fast the p3-550 @ 825/150 will finish a wu in? i checked out the database and it seems that most of them get to 825 easily, even with the old ca2 stepping.

 

[Fingers]

also, hardware central has a lot of info on seti@home, and i believe they have made list of CPU performance in seti. Chack there site out for more info.

 

[MegaManX4]

come on guys, no one here with an Athlon/Thunderbird?

It ts true that the older clients (´GUI 2.04 ect.) were really not good for the athlon platform. Especially the thunderbirds really sucked. but, with the new clients (anything above 2.70) are giving me really good numbers. my thunderbird 700@900 crunches a WU in about 4hrs and 15min, not bad if you ask me. a colleges duron 600@900(WOW!) needs sometimes 20min more. both are on a 100Mhz bus

 

[TuffGuy]

MegaManX4 - Finally!!! someone with a t-bird posts their time. i always wondered what the fp power of the t-bird could do. my p3-700@1000 does packets anywhere from 3-4hours. i'm curious as to what a p3-550@825 does though, since the new seti clients are bandwidth limited. IF the 150mhz fsb helps it finish packets as quickly as mine it would be awesome.

but so far nobody has posted their time.

 

[BurntKooshie]

at this point, the main limiting factor of the T-bird is the chipset. Anything from VIA basically sucks compared to intel's BX chipset as far as memory latency. Right now, that's a major factor. The FPU would be able to tear through stuff if it was fed in a timely fashion, which its not.

 

[Sukhoi]

Yeah, I'd say a PIII 550 OCed to 825 on a 150 MHz FSB on a i440BX board with CAS2 RAM would have to be one of the best bangs for your buck you could possibly currently get for SETI. This may all change once the new clients are out though.