Quick question about l2 cache

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fedshark

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Jan 21, 2006
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At the moment, Im using a p4 2.8 gig 800mhz fsb with a 512k l2 cache. If I upgraded to a cpu with a 1 or 2 mb cache, would I notice any real difference?
 
Cache size alone doesn't make a huge difference in performance once the size reaches a certain threshold. In general, performance increases are apparent only in certain applications when moving from 512k to 1MB L2 in the A64 and 1MB to 2MB for the Prescott. Clock frequency provides a more reliable global performance increase.

In your case, since your P4 has a 800MHz FSB and 512k L2 then it most be a Northwood C. The Pentium 4 processors with more cache are Prescott cores and are quite different. While they do have more cache, that was necessary to make up for the inefficiency of the lengthened pipeline. For you to match the performance of your 2.8GHz you would probably need to look at at least a 3GHz or higher Prescott.

A lot of it depends on what type of applications you are running. In games, the Northwoods beat their Prescott cousins at the same clock speeds while in media encoding tasks the Prescotts are faster due to SSE3 and more cache. It would be helpful to know if you are planning on just switching processors while keeping current motherboard, etc and what your current configuration is.
 
Let me see how well I remember my config offhand....

P4 478 2.8 gig 800 fsp 512k l2 cache ht cpu
MSI 865PE neo2 PFS platinum, I uh, think
1 gig dual channel ddr 400 ram
geforce 6600 256mb agp (planning on upgrading)
ultra xfinity 600 watt PS

I think thats all thats worth mentioning. Im going to upgrade my computer soon to run the higher end games like Oblivion, and I havnt been sure whether or not the CPU would be worth upgrading along with the video card. If I dont flat out splurge for a pci express compatible board and have to buy a new cpu altogether, anyway. From what you've said so far, doesn't sound like my CPU will really need to be upgraded just yet. Still need to consider whether itd be smarter to buy a 6800 gs or xt, or just flat out overhaul my mobo+cpu+vid card with a socket 775 and possibly a geforce 7800. I dont know if I should spend that kind of money, though.
 
I'm not sure what I'm saying here, but I think you might encounter a problem if you're deciding to keep your current processor and buy a new motherboard. I don't think your processor will fit into the new motherboard that has PCIe. I believe I have the same processor as yourself and I couldn't find motherboard that'd support my processor and offer PCIe interface.
 
Ok Im assuming that your 512kb cache p4 is a Northwood.. and the 1-2mb cache is the Prescott. The prescott has longer pipelines than the northwood which requires more MHZ than the northwood to actually meet its potential, but at the same time, the prescott has an insane heat problem...so theres no point in upgrading anyways.

2.8 Northwood 800fsb.. hmm should be very overclockable anyways...
 
Let me see how well I remember my config offhand....

P4 478 2.8 gig 800 fsp 512k l2 cache ht cpu
MSI 865PE neo2 PFS platinum, I uh, think
1 gig dual channel ddr 400 ram
geforce 6600 256mb agp (planning on upgrading)
ultra xfinity 600 watt PS

I think thats all thats worth mentioning. Im going to upgrade my computer soon to run the higher end games like Oblivion, and I havnt been sure whether or not the CPU would be worth upgrading along with the video card. If I dont flat out splurge for a pci express compatible board and have to buy a new cpu altogether, anyway. From what you've said so far, doesn't sound like my CPU will really need to be upgraded just yet. Still need to consider whether itd be smarter to buy a 6800 gs or xt, or just flat out overhaul my mobo+cpu+vid card with a socket 775 and possibly a geforce 7800. I dont know if I should spend that kind of money, though.
Click to expand...


A couple of things:

If you want to keep your CPU and AGP mainboard the best AGP card is the x850xt which has been found for about $200:

http://www.newegg.com/Product/Product.asp?Item=N82E16814102505

The 7800 is AWESOME. What socket do you have? There is a PCI-express board for socket 478 if you want to keep your old CPU.

http://www.asus.com/products4.aspx?l1=3&l2=12&l3=0&model=942&modelmenu=1

I'll be back in a minute with the links.
 
My recommandation for the CPU would be to get some DDR500 and give the processor a good OC.

If you have a good one, you could get it to around 3.4 ghz no problem on air cooling. My 2.6 will do 3.4 and above on air at around 40-45c under load!

Then for AGP video card, you could try to find some fair price on X850/X800 and maybe spahire will release something faster than a X1600XT...

Update: here's what I found on the vid cardz forum...
X850XT 200$

Damn its PCIe but you get the idea :?
 
Your current configuration isn't bad. The best course of action would probably be to keep your current processor and motherboard. There isn't really a reason to go to the trouble of changing to a motherboard that supports PCIe since your upgrade paths are still narrowed by the processor and platform generation. Personally I'm not much of a fan of VIA chipsets anyways.

It would much more worth to just get a new AGP graphics card. Good cost effective graphics cards include the ATI X800GT and X800GTO. The X800GTO are especially preferable since they are generally built on the R480 core meaning they have great overclocking potential. If you want the latest generation, then the X1600 is now available for AGP providing SM3.0 support and hardware video encoding and decoding. I'm not as sure about nVidia's offerings in the AGP market, but the 6800GS is now available in AGP. The X800GT and the X1600 Pro retails in the $100-$150 category, the X800GTO in the $150-$200 category, and the 6800GS in the $200-$250 category. As someone else has mentioned before the fastest AGP card currently, and probably ever since the 7800 and X1800 won't be offered in AGP, is the X850XT PE.

Most modern games are more limited by the graphics card than the CPU, so its more cost effective to upgrade the GPU. If you really wanted better CPU performance, you can just overclock it.

Argh. I walk away from my computer to do something before completing the post and someone has posted what I was going to say. Oh well.
 
Thx for all the input so far everyone. After seeing that s478 pcie mobo now I'm wondering.... How much of a difference would it make if I used that mobo and bought a x1800 or 7800 with my current cpu compared to a newer mobo with something like a dual core amd or EE pentium with the same video card? Would it be wasteful to have a high end card, just to be using it with a s478? I might actually be willing to pay for that mobo and a pci e card if its worthwhile, and not going to just waste my money in the end because of the socket type holding my performance back.
 
I'm glad you asked that question. The answer depends on if a game is CPU or GPU bound. I'd venture that the GPU is by far the most important for gaming, however the other stuff helps too. Spend some time pouring over the benchies to get a feel for what makes the difference.


For example there are a bunch of us that have 7800 GT cards and we all benchmark a little different from one another but we still all fall in the 7-8k range (3dMark 2005) reguardless of CPU (within reason).

Honestly I think your best bet would be that AGP x850 XT for $200. It 3dMarks at around 6k.
 
If you are seriously looking at the very top end of graphics cards like the X1800 and the 7800 then you really aught to consider getting a completely new system. If you are willing to spend the money, high-end dual cores like the X2 4800+ or 950D or higher can offer great gaming experiences since background processes are offloaded to the other core. It's generally thought that single cores offer the best gaming performance for the money, but if you can afford one of the higher clocked dual cores there's no reason not to get one especially with newer games and graphics card drivers now support multithreading. If you are mainly looking to just game then an AMD would be a great choice. The dual core Opterons are of particular value for their overclocking potential, but you'll have to hurry since supplies seem tight with AMD increasing Opteron prices soon. AMD is also planning on lowering the price of the X2 to make it more competitive with the Opteron and Intel's new 9xx series.

Even more important is the fact that the latest hard drives offer SATA II and more cache for higher burst speeds as well as better components for higher sustained speeds. Since the hard drive is the slowest component of a system, newer ones would be most beneficial. If you really want to spend the money the new 150GB Raptors are great for gaming.

BTW, if you are looking at the X1800 or the 7800, you should wait a week or so since ATI will be releasing the X1900 on Monday. It should be much faster than X1800 and the 7800 if you are willing to spend the money and it'll drop the previous generations price.
 
...especially with newer games and graphics card drivers now support multithreading.
Click to expand...

I think you mean Multi-tasking.

BTW, if you are looking at the X1800 or the 7800, you should wait a week or so since ATI will be releasing the X1900 on Monday. It should be much faster than X1800 and the 7800 if you are willing to spend the money and it'll drop the previous generations price.
Click to expand...

I though they were going to release the X1700 series, what happend to that!?
 
In the case of newer games and the new graphics card drivers those are multithreaded. Multitasking through dual core load distribution only needs to be supported by the OS not the program itself.

There is a replacement for the X1600 planned probably using 80nm but I don't think they've formally named it yet. Actually there are two replacements for the RV530 X1600. The RV535 is supposed to be a RV530 respin in 80nm while the RV560 is a redesigned RV530. I'm not sure if the RV560 will be 80nm based, but it presumably will be to keep the costs down. The RV560 will probably be called the X1700 while the RV535 may just be drop in replacements and keep the current X1600 names or the 80nm process may offer more clocking room and be called the X1650. Neither will likely be released until the end of Q1 at the earliest though since the X1600 is just starting to ship in quantities. The X1700 would be ATIs response to nVidia's 7600 which hasn't launched yet.
 
Very informative Mr.Data.
Howerver
Multitasking through dual core load distribution only needs to be supported by the OS not the program itself
Click to expand...
may not represent the advantage of the newer drivers. They are actually enabling the gpu to multi-task with the unused cpu core. This is not currently supported by the OS.
Unfortuneatly, this is not as advantageous as it sounds. The specialization of gpus make them more efficient at most gfx intensive progs. The latency between the gfx card and the cpu is also a detriment. Still, there is some advantage.
 
In terms of my multi-tasking sentence I was more referring to the ability to run one application on one core and another on the other rather than the new graphics card driver's ability to multitask with the CPU. I believe those new dual core graphics card drivers are rather finicky though. Supposedly they have some problems running with dual core compatible games either because the game doesn't like the GPU trying to hijack the extra core for multitasking or the multithreading support of the drivers conflicts with the game's built in multithreading support.

I've only heard of the problem for the nVidia drivers though. For Forceware 81.95
http://www.xbitlabs.com/articles/cpu/display/presler_14.html

and Forceware 81.97
http://www.xbitlabs.com/articles/cpu/display/athlon64-fx60_11.html
 
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