FSB performance impact question

[Frank]

Hi, while I search thrue the forum to see if there are already answers to questions I have regarding MWO then I got this question for you tech-wizards.

I got an Asus P5Q-SE motherboard and 2x1gb Kingston HyperX Dual-Channel RAM. This motherboard is said to be able to have 1600MHz FSB some places, and 1200MHz for the RAM however for the RAM to hit 1200MHz then I need to adjust the BIOS-settings with settings listed in the motherboard manual. Some times this just doesn't work and when I boot then there's a message there was a failure and it's reverted to default values. I haven't figured out what triggers this though and I have just run with default settings for a long time now which would mean 1066MHz for the RAM.

What I'm wondering is if anyone has an idea on how big an impact, if any, the slower FSB would have for general software use, sim-racing, video-editing and such?

Frank

[Chaul]

The answer depends a little on where the memory controller is (motherboard or cpu). Just to keep that in mind, your motherboard is one that has the controller on the motherboard separate from the CPU (and actually has the FSB). With the other option things get a little different, and I'll leave that out.

Ok, on the FSB issue, the FSB is the bus between the CPU and Northbridge chipset, and in this case the Northbridge handles the memory bus. You should also note that most processors are locked to a certain multiplier, and this multiplier is what decides the running frequency of the processor in relation to the FSB. Differen CPU models are also specified to run at certain FSB rating.

Keeping the multiplier locked and raising the FSB, you are effectively overclocking the CPU and possibly other things (memory and PCI bus?) which I'm not too sure about. If it affects PCI bus, it also affects the cards on the bus that depend on the PCI bus frequency. However it's mostly the cpu and memory, and possibly the motherboard chipsets that get strained here and can cause you that "error". With graphics card, you mostly get artifacts, geometry errors or blank screen, when overclocking.

The thing about settings reverting to default (overclocking failure?) is a safeguard feature. Motherboard decides that things are not running reliably (high temperature sensor readings, memory errors caused by high frequency or other too optimistic settings, previous hard crash?). There are several memory settings that can affect reliability for example. On one of my old motherboards, as soon as I changed settings to manual from automatic, even with very conservative settings, I would get an overclocking error on the next reboot, and I never learned which memory setting was wrong etc..

The fact that the motherboard could handle a higher bandwith on the memory or the FSB, does not mean that your cpu and memory could in your environment (ambient temperature?). Components are individuals and can be different with what comes to overclockability even if they came from the same line and were built on the same day.

I don't think RAM frequency matters that much on its own, but the FSB can easily affect all kinds of performance. Then you can debate on the FSB/memory bus relation and would it be beneficial to keep that 1:1 balanced - I don't know. The question is, do you want to risk stability for the slightly higher performance benefit. You'll just get more random crashes if you don't also take care of cooling.

Games benefit from a good graphics card. Video-editing is debatable because it's mostly taxing CPU and memory too (at least in amount), but with the latest video-editing apps you can also benefit from the graphics cards ability to accelerate some of the operations.

[Frank]

I hope this reply gets posted, I keep getting logged off everytime I try to post.

I've tried looking thrue the BIOS menu again and in the FSB setting menu for the RAM then 1200MHz is listed with ** around it and there's both 1334 MHz and several speds way under that, couldn't that mean 1200MHz is the optimum speed? I tried to set it manually but the machine crashed on start-up. It's actually really hard to guess what settings/speeds this machine runs at, or if it's even running anywhere near optimally.

Frank

[gcountach]

Quite honestly, for normal use, I don't think you'll see a noticable performance gain going from 1066mhz to 1200mhz.. but it will cause quite a bit of headache trying to achieve that. Like Chaul said, changing the FSB can cause cascading problems. CPU speed is FSB x Multipler. You change the FSB, you've just overclocked your CPU. This is the most likely cause of your computer crashing on startup.... your CPU saw what you changed its speed to and goes "umm.... no".

FSB of 1066mhz, and you have say a 3.0ghz Processor
1066 x ~3 = ~3.0ghz

Now if you have 1200mhz...
1200 x ~3 = 3.6ghz

That's a pretty significant boost in speed... one I don't think the CPU will like....

Take a look at this link: http://en.wikipedia.org/wiki/DDR2_SDRAM#Specification_standards

As you can see, the max speed that's in specs for DDR2-RAM is 1066mhz. Anything above that and you're in some unfamilar territory.

To sum it up, it's not worth the risk or effort to make your RAM go 1200mhz. Keep in mind that severely overclocking something can cause damage, but more likely scenario is the computer will be very unstable, which makes it pretty useless.

[Wraith]

You probably don't realise all the places you are affecting adjustments when you simple increase the FSB. There is usually a memory divider option which you should be using to increase the ram speed without increasing the speed of the cpu. Not doing that and bumping up the FSB will also overclock the CPU (as you've already been told). However, pushing the memory speed up without loosening times can also be the cause of your crash.

Frankly, there is almost no impact whatsoever from memory speed increases. The cheapest DDR2800 performs about the same as the most expensive DDR3 with the tightest timings in almost every application. The only place you'll see an increase is in some video editing apps if I remember correctly (and even then it's at most 5%).

Bear in mind that this only relates to your system (P5Q means you're using Core 2), and that this doesn't apply to all generations of different brands of CPUs.

Increasing the CPU and GPU clocks has a far greater impact in more intensive applications.

[Frank]

Thank you for the helpful replies. I have to admit that I don't know much past the basic specifications. I just read that officially this motherboard can run 1200MHz FSB for the RAM and I waited several weeks to get the special RAM delivered and now it looks like I wasted both time and money.

This is the first PC since my first in 1998 (I had Amigas before that, and still do) that doesn't have the same FSB speed for all main parts and I've basically thought/hoped that having all parts able to run at the same FSB speed would be an optimal choice for overall performance. For this motherboard however I can't figure out how to run the RAM at the speed they are made for and which all official documentation says the FSB can run at. I find it really strange that a producer would list maximum performance which is only achieved using overclocking settings. It's like a car-manufacturer selling a car with 200hp and listing the max power as 225 and then in small letters saying: Requires adjustment of the carburator.

Frank

[Tomh]

Frank, I hope this doesn't insult you, as it isn't meant to, but I can tell that you don't know a lot about overclocking computers. It has been my experience that those who don't really know a lot about what they are doing when changing bus speed, and overclocking computers almost always do serious damage to their machine. You do need to realize that messing with those settings can lead to a complete failure of your processor, your memory, your main board, and perhaps other peripheral cards (like your graphics card).

In addition, you really aren't going to realize any great performance increase by changing those clock speeds, honestly, you're not likely to even get a noticeable improvement. The only thing you are likely to notice is that your computer is much less stable, crashes more often, has weird issues with the graphics / displays.

The best advice I can give you is to go into your BIOS, load the failsafe defaults, save them and leave it alone. You, and your computer will both be much happier that way in the long run, I promise.

[Wraith]

Usually there's the Load Optimized Settings. Failsafe settings usually cripples the system. I'm not going to get into it about overclocking, stability, and what not, but I agree that in your case, Frank, just let it be. If you want to research it and learn, good on you.

The interesting thing about what you mention with the RAM is that it's considered a feature. The RAM is rated at a certain speed, but to make it backwards compatible with motherboards it defaults to a lower speed (not all RAM is set up this way, but I know a lot do). If you can't boot the system because your motherboard won't run at a frequency, you'd be more annoyed than you are with your current issues.

[Tomh]

Right you are Wraith, I don't know what I was thinking, but indeed it is the optimized settings you want to load and save, NOT the failsafe settings

[Frank]

Thank you for trying to help, I appreciate it, and I took no offence, especially since you made it clear it wasn't intended as such. It's actually been a while since I tried to get it to work so there are probably some important details I've forgotten. I'm usually satisfied with how things work in stock configuration and am well aware that every thing affect each other however I just rememebr reading in the manual that it was made to run 1200MHz, and that I just needed to adjust the default BIOS setting to achieve it. It does however sound more and more like the motherboard wasn't designed to run "normally" at that speed.

As far as I remember then the BIOS reverted to default settings, not a failsafe, and on all previous machines I've had then the default settings worked just fine with the parts I had. I think I need to refresh my memory and read the motherboard manual again and see exactly what it said was needed to be done to get the 1200MHz and what it says about any consequences with those settings.

Thank you again for trying to help, I'll get back to you when I've dug up the manual.

Frank

[Tomh]

Depending on the particular main board you have, it is sometimes possible to have the FSB and memory running at different speeds. This is the case with my current system. The memory is running at a faster rate. I'm not certain what kind of performance increase this leads to, if any, and it certainly isn't worth doing if it is going to introduce any sort of instability to the system, but what you are looking for is a setting to have the memory asynchronous with the FSB so that they can run at two different speeds.

[Chaul]

Often there are multipliers or ratios, so that the memory can run at default ratings even if the FSB was overclocked or the other way around. DDR2 800 is pretty default to me, these days it's probably 1066Mhz though.

Also, the DIMM's often have one or more SPD profiles, so at a certain frequency you can let them pick the other settings, like CAS, from the profile or something like that, or force it outside of the SPD rating.

I know what you are saying about spending on memory. I have always spent too much on performance memory, only to realize the lower spec would have given me the same result, considering that I was unable to overclock it after all, or chose to run it at default anyways.

[Tomh]

Overclocking is hugely dependent upon your ability to remove large quantities of heat from the system, and it's individual components very efficiently. There are some success stories with overclocking, however most of them rely on expensive, and often complicated cooling systems. Most of the time, the risk, cost, and aggravation associated with overclocking a system more than offset the small performance gains that are possible. The bottom line is if you want it to run faster, spend your money on a faster machine.

Sure you can dump a 400 HP shot of nitrous into your 1.2L 4cyl, and make it run like a 350 for a little while, but in the long run, you'd be much better off spending your money on a 350 to begin with.

[Wraith]

I didn't want to get into it, but since you brought it up: that's completely incorrect.

Let's take an example system with a 1.8ghz dual core, either amd or intel core 2. Bumping the FSB, changing the multiplier, or changing the ratio between FSB and memory and yielding a result of say 2.2ghz would have almost no impact on temperate at load. Only increasing the vcore would have a significant impact on temperatures.

In fact, the Q6600 core 2 Quad typically requires no vcore when bumping from stock (2.4ghz) to 3.2ghz. Yes, there is a tiny increase in temperature at load, but nothing like what you're talking about and easily able to be handled by the stock cooler.

Now on the issue of coolers. A cooler like the Scythe Infinity (http://www.frostytech.com/articleview.cfm?articleID=2214) is not expensive at all and is exotic while providing fantastic cooling regardless of whether you're heavily overvolting or running stock.

You can actually overvolt a CPU without increasing the CPU speed and watch the temperature go way up.

If you don't know what you're doing, yes, you're more likely to have issues in any technology. If you know what you're doing, you're only going to encounter issues when you push the CPU beyond a point of stability, which is, in today's generation of CPUs typically in the range of 1000mhz on mid range intels, and perhaps 600-800 on mid range AMDs. Using a percentage relative to the stock clock would probably yield a truth value for any generation CPU.

These are computers, so your analogy is very oranges to apples, and I don't think it can be really equated. The best thing I could say is it's like this: Each CPU core generation (kentsfield, yorksfield, etc) is released like a set of cars with different ECM settings. More specifically ECM settings restricting speed. Overclocking is like removing the ECM limit. The car was always able to go that fast, and if you're smart, you'll buy the cheap low end which has all the same technology (cache size mostly), and overclock. You'll almost certainly have 100% stability at the clock speed of the highest released clock speed of that same generation.

I could assume you mean overclocking beyond that point, but since you say "spend your money on a faster machine" that mean you are talking what's retail stock. And for that I would reiterate overclocking a low end of that same technology to the clock speed of the highest clocked retail version of that generation will almost certainly be 100% stable. It really depends on how you're overclocking it. If you have to overclock the FSB by a tremendous amount due to not having the ability to alter the CPU's multiplier, you're more likely to encounter issues. A good motherboard will let you avoid this problem at least to any retail clock speed.

If you were a CPU manufacturer, and you made a whole bunch of CPUs, and all them were able to run at high speed, would you sell them all at the highest tested clock speed? Then they wouldn't make an profits, since everyone knows the majority of CPU profits (and indeed any computer part) come from low to mid range. So you sell a bunch at speed x-5, a bunch at x-4, etc all the way up to super elite X model! Sorry, but I've been running overclocked systems for over decade 24/7, home servers, htpcs, and desktops, and never have had stability issues after the initial setup (testing to find the highest stable clock frequency and overvolt). The only stability issues I've ever encountered is from faulty products which get RMA'd or incompatible drivers screwing things up.

If you don't know what you're doing when overclocking, I completely agree. It's not worth it. If you are willing to learn, it's definitely worth it. If you already know what you're doing, it's a given you will, and that you bought the system you're overclocking with that in mind.

I don't mean to argue or to offend you, but I'm just giving my input on something which, in my opinion, is incorrect. Extreme overclocking is one thing, moderate overclocking is another. I think my ECM analogy is a close one to what you're actually doing when moderately overclocking.

[Chaul]

Yes, the process goes like this, first they have a set architecture, the design of the cpu, and start churning out cpu's. Pretty much all the cpu's coming from the manufacturing line are the same, but in the end they get tested to see at which GHz setting they can sell it at. I hear that sometimes they are forced to label some cpu at a lower bin, because they aren't producing that GHz labelled processor enough, even if technically it could perform at a higher GHz rating just as well. For example, AMD sells 3-core processors, but they are just 4-core ones with one of the core's disabled, possibly because of a manufacturing error in that core, "possibly". There was even a "hack" to re-enable that disabled core on some motherboards or settings. Also, you can get lucky and get one of those golden processors that could perform a lot better than what they were sold as..

I am just slightly "bitter" regarding overclocking, because I have not been very successful in that yet, except for overclocking one Radeon 9800 with help of some software tool. CPU, not so much.. I tried overclocking a P133 once, but that effort was doomed because of bad motherboard settings - never could get it to work at 166Mhz. So, I tend to give advice against overclocking, or "be very careful". In any case, do it in small steps! (and, don't count on it to work). These days overclocking is easier and more likely to be a success.