Quad with slow memory

[db597]

I'm thinking of upgrading my dual core E5200 to a Q9450. The problem is the existing memory in that PC is DDR2-667MHz (dual channel). I remember that memory bandwidth is a bottleneck on quads even up to 1066MHz dual channel and performance doesn't scale well.

What do you guys think? Is the upgrade worth it? What can I run that won't be bottlenecked by the memory? Perhaps 2 instances of P95 and another 2 instances of some other distributed project (f@h, wcg etc)? Do you know of any projects that are not memory intensive?

[Batalov]

I do recommend to spend extra $29 for a 2x1Gb 1066MHz (really, not a big pain these days; not a hundred bucks as it used to be); or better yet 2x2Gb for under $40. Just get some best-egg-rating memory (I will deliberately not bias you toward any brand), not the cheapest; it is worth extra $5.

(The only concern is: Does m/b support 1066Mhz? Research.)

[Mr. P-1]

Originally Posted by db597

Perhaps 2 instances of P95 and another 2 instances of some other distributed project

Or two threads devoted to LL testing, and 2 to low-memory-bandwidth factoring.

[joblack]

I bought 4 - 2 GB PC800 DDR2 pieces for 15 Euro each ... works like a charm with 395 x 9 ...

[KJohnson]

Well, theoretically if you run two CPU intensive programs that don't use much RAM, you will simply double your computing power.

If however you try to, for example do P-1 factoring on multiple cores, I think your throughput would be noticibly less.

[db597]

Thanks everyone for your responses. Seems the general opinion is that for a quad it's worth upgrading the memory as well. I did a search for memory prices, and see that entry level DDR3 1333 is now within a few dollars of DDR2 1066 memory. Quite surprising, I had always thought that DDR3 was double the price.

I might just hold out another few months and go with the new Intel i5 when it hits the market. I suspect the i5 will be around the same price as a 9450 quad. The cost difference between the 2 routes would thus only be the need for a new motherboard. But in the long run it makes more sense, rather than to be pouring more dosh into a DDR2/Core2 platform.

[VJS]

Yup your probably past the point of upgrading that E5200.

2 Months ago it would have been worth it, now not so much. i5's will probably be at or less than the 200 mark in a few weeks. What we don't see yet is MB prices whihc could make or break the deals.

I never fully understood this topic really. I have always been interested in getting a G5, ever since they came out. I might be able to nag a Quad G5 for very cheap, but I have a question. I know that an Intel Core 2 Duo is faster than a G5, but how is it faster than the Quad? What exactly makes the Intel faster than the G5?
So, what makes the G5 Quad, or even Dual Core/Dual Proc G5's so weak?

[cheesehead]

Originally Posted by mariajones

I know that an Intel Core 2 Duo is faster than a G5, but how is it faster than the Quad? What exactly makes the Intel faster than the G5?
So, what makes the G5 Quad, or even Dual Core/Dual Proc G5's so weak?

Simply, Intel CPUs have faster optimized floating-point execution than Apple CPUs, even at the same clock speed. (In the recent Apples that can run Intel code, it would still be the Intel FP code that is faster than Apple FP code.)

1) Intel FP registers hold 80-bit values internally, whereas everyone else's AFAIK, including Apple's, hold only 64-bit values. This means that optimized FP instructions at the heart of FFT computations can be designed to handle more data bits per FP operation on Intel than on Apple.

2) The Intel FPU could process (at least, it used to) more instruction stages simultaneously than the Apple FPU.

Both those factors result in faster throughput of FP arithmetic results on Intels.