Performance increase of 939 over 754

[Dan G]

Hi! I have been using an OC'd AMD64 NewCastle 3000+ in my pooter since January, and its on a DFI UTNF3 socket 754.

Now from what I have heard the actual performance increase available for similar gear whilst using 939 is very little. What I am saying is, if I left my rig alone, changed the mobo to a 939 and another AMD chip with a 939 core, same clock speeds and same caches, what would I gain?

I know that would be a dull upgrade, but I'm talking theory anyway! Most importantly, why is 939 better over 754? I'm geussing this will involve memory controllers!
Thanks, Dan

 

[Bona Fide]

It wouldn't be out of this world, but you would get the addition of dual-channel memory support as well as a better memory controller. And that's just on the chip. Venice processors also overclock better, use less heat, and are more energy-efficient.

 

[Dan G]

Ok right. I have found my NewCastle OC is limited mainly by my RAM, GeIL Value PC3200, 1Gb of it. It couldn't hack it above about 226Mhz, so it's on a divider to keep it down to that. I feel that I could get a better increase by getting some quality RAM (G Skill, OCZ) that could out pace my CPU. What are your feelings?

And please, can you go into some more depth of what you said in your post? Particularly the issue of Venice's out OCing SanDiego's over L2 Cache size. Why is that?

 

[the cobbler]

bigger cache=extra heat, 1mb on San Diego, 512k on Venice

that heat alone can contribute to a slightly lower OC ceiling than the Venice, which runs much cooler

 

[the cobbler]

why don't you try dropping down to a lower divider so you can raise your CPU speed, you should have no problem hitting 2.4ghz

memory dividers don't really hurt you on Winchesters/Venice/San Diego, etc. because of the on-die memory controller. I don't know how much they will hurt you on a Clawhammer but I would guess the extra 150-200mhz CPU speed would more than make up for it.

I run my value PC3200 on a 140 divider to keep it around 220mhz at good timings (for value ram lol). My FSB is at 305. Learn to love your memory dividers

I would also save yourself the cash on the RAM and seriously consider selling off the 754 setup for a nice 939 board and a Venice 3000+. Probably similar price to 1 GB of very fast ram. that way you could hang on to the value ram for the time being and count on about a 2.7ghz processor speed.

 

[RichUK]

a better OC if that is what you are interested in

 

[coomar]

going up a divider is like adding 50mhz roughly to performance, so going down would be the same

 

[Aenslead]

Well, here I go:

No, the performance increase over the cost IS NOT WORTH IT, unless you are considering a significant upgrada, that is, like an X2.

The performance advantage you could expect are about 5-7%, from which 0-3% are due to the dual-channel memory controller, and the other 2-4% more is due to the core upgrades and enhancements.

In my opinion, your OCed Athlon 64 performs just about as a 3500+ Socket 939 processor, given the aditional FSB it gets due to overclocking; should you change, you will not notice any advantages in performance.

I recomend you:
a.- change to Skt939 IF you plan upgrading to an X2 processor
b.- dont change at all and wait for socket M2.

Good luck.

 

[Hacp]

Originally posted by: coomar
going up a divider is like adding 50mhz roughly to performance, so going down would be the same

Nah, less than that. Compare the 2nd ram vs the 3rd ram. The 2nd uses the multiplier with DDR400 to get to the speed. The 3rd one uses a lower multiplier, DDR400, but also the divider. Almost the same performance. It looks like less than .5%.

http://www.xbitlabs.com/articles/memory/display/ocz-ddr600_4.html

 

[Aenslead]

Memory bandwith matters little to single core AMD processors.

 

[coomar]

that just shows that running a divider is the same as running 1:1

 

[Aenslead]

Its not the same...
It simply doesn't affect real world performance.

 

[bunnyfubbles]

The performance increase is 2times the cores, because you can't get dual core on 754

Otherwise the 754 A64's can still very much hang with the 939s. I think the only way you'll notice much difference at an equal clock is if you're running a 1MB L2 cache 939 in dual channel with an SSE3 core and then clock for clock you might have something noticable.

However, chances are (if you do upgrade to 939) that you'll see much higher speeds than 2250MHz and thus clearly more performance. However even 754 @ 2.25GHz is still respectable in the enthusiast world, I wouldn't upgrade to 939 unless I was getting X2 to go with it. But that is just what I would do.

 

[Hacp]

Originally posted by: Aenslead
Its not the same...
It simply doesn't affect real world performance.

Ya, def not the sam. There is still that .5% performance difference .