confused: Athlon 64 purchase

[KimB]

That's a good sign. Are you running XP SP2? Perhaps MS has updated the scheduler.

Yeah. But it'd probably be a good idea to go back and double-check this. I haven't looked at CPU usage in games in a month or two, so it'd be good to analyze it with some rigor.

 

[the maddman]

Yeah. But it'd probably be a good idea to go back and double-check this. I haven't looked at CPU usage in games in a month or two, so it'd be good to analyze it with some rigor.

Better make that a new thread, I think we hijacked the "Which A64 to buy" to much.

Sorry about that deviantchild, hopefully we're giving you usefull info while we discuss otherthings too.

 

[Frank]

About the original question: the cheapest one of those will be best, if you look at the price/performance bit. Very roughly, you pay almost twice as much for about a 10% speed increase. That makes overclocking a no-brainer if you want the fastest.

Then again, they're all so fast, that you won't really notice the difference in speed in any case. So if you go for price/performance and stability, the cheapest Venice is the best. That's what I would buy.

 

[Diplo]

Definitely don't bother with one with 1MB cache because it makes little difference in most apps.

Personally I would go for an Athlon 3800 X2 (which, incidentally, I may well actually buy soon) because I think this offers best value. Whilst there is little software that properly takes advantage of dual processors/cores I think that will change in the near future. Therefore you could be in the situation were your machine actually performs better in the future, which would make a nice change in the world of PC upgrades! In the meantime you would still enjoy very good performance in single-thread aps whilst having your general computing experience enhanced by being in a more responsive environment when multi-tasking. I also believe the 3800 X2 will easily clock to a 4200 X2 for most people, with decent cooling.

 

[Gubbi]

That said, I don't think there should be much of a performance hit from switching tasks between the CPU's on the Athlon X2, due to the existence of a high-bandwidth dedicated lane between the two CPU's.

It's not the bandwidth, it's the latency.

Normally you'd see a 95% hitrate in the D$ and I$, 98% hitrate for L1+L2 caches. This gives you an average memory latency ~3-5 cycles. When you switch core, every memory access causes a miss and have to spend >20 cycles to get to the caches on the other core to get the data.

In CS:S I see 20% lower performance in in-game situations, and it's the anoying kind, not just average lower framerate, but "hickups".

The fact that I didn't reinstall XP when I dropped my X2 in my existing motherboard might have something to do with.

Cheers

 

[the maddman]

It's not the bandwidth, it's the latency.

Normally you'd see a 95% hitrate in the D$ and I$, 98% hitrate for L1+L2 caches. This gives you an average memory latency ~3-5 cycles. When you switch core, every memory access causes a miss and have to spend >20 cycles to get to the caches on the other core to get the data.

In CS:S I see 20% lower performance in in-game situations, and it's the anoying kind, not just average lower framerate, but "hickups".

The fact that I didn't reinstall XP when I dropped my X2 in my existing motherboard might have something to do with.

Cheers

There are two different HAL's depending on if you install on a SMP box or not. It seems from some googling around that XP can switch HAL's for you, where win2k would not. I'd have to do some experimenting to figure it out and since I don't have a dual core yet, I really can't say for sure.

If anyone that wants to mail me a X2 I'll be sure and test things out!

 

[maaoouud]

If you're willing to spend the money, opteron 165 is the cheapest and best dual core (with a "minor" overclock.. say 2.2-2.4GHz without raising the voltage, it should be quite stable).

I'm not keeping track of the cheaper ones, single core, tho. But from what I hear there the single core opterons are best value too, however this is from overclocker fanatics and you're not. You may very well be quite satisfied with one of the cheaper cpus.. say a 939 sempron. As others have pointed out, with the K8 it's mostly clockfrequency that determines the speed on these chips so going from 256k to 1meg L2 cache is less important.

 

[Tahir2]

Cache is important depending on what you are doing so if it is mainly games then cache is not so important.

In this case I would go for a standard A64 3200 or 3500 if your budget allows for a DC then go for one of those.

 

[deviantchild]

Right...

@ Gubbi, Chalnoth and Maddman: NP with the hijack. Part of the reason I create slightly ambiguous threads sometimes is to encourage any related discussion at all.
(@ Maddman: [On the subject of HALs] Yeah, you can force them at installation. Windows can sometimes get it wrong and if it does and you try to change it back you can end up with a completely unrepairable OS - with various HW missing - as I did once!!!)

@ DiGuru: Some sage words there - guess you earned that moniker of yours

@ Everyone else: Thanks for the affinity/scheduler input - I'm sure this will get swept up and resolved fairly swiftly as per future computing requirements dictate the need for workable solutions.

@ maaoouud: No Sempron for me right now as I'm already coming from an XP3000+, which I can no longer use as my MoBo appears to have gone irreversibly doolally

So...

I can get the Athlon 3800+ X2 for £231.29
or the Opteron 165 for £222.08 from the site listed in my initial post

It's looking like the Athlon is ahead in the stakes slightly but I'm still intrigued by the Opteron


Thanks all,
I hope some other folks who are out-of-the-loop, as I was, may find some useful info in this thread.