Overclocking Basic Tutorials
Tip #4
There are a lot of PC Modders who want to overclock their rig, but it seems many don't understand the basics. To help them out, I had written a series of articles, Unfortunately, new posts in the overclocking section are bumping them downwards, and many are simply not aware that they exist.
This post creates an index to those articles.
Overclocking 101: CPU Performance - Its all in the bus speed
Overclocking can be done by raising your CPU speed without changing the front side bus (by goign form a setting of 13x133 to 15x133) or by increasing the front side bus. However, overclocking your processors front side bus gives you more benefit than just raising the processors total speed.
Test chip: XP2100+
Platfonm: NForce 2 Ultra 400
Memory: 2x256MB Dual Channel (2-3-3-11)
Benchmark: Super Pi 1M (compute the value of Pi to the one million decimal place)
At default the calculation is completed in 62 seconds.
Next we raise the front side bus from 266MHz to 333MHz but dropping the
multiplier from 13 to to 10.5. This results in a speed gain of 20MHz, but that is too small to affect our testing. At this setting the calculation is completed in 58 seconds. Thats a performance increase of 7 percent.
Next we raise the front side bus from 333MHz to 400MHz but dropping the
multipler from 10.5 to to 8.5. This results in a speed loss of 33MHz, but
agian, that is too small to affect our testing. At this setting the
calculation is completed in 56 seconds. Thats a performance increase of 11
percent.
1733MHz (13x133) = 62s
1754MHz (10.5x166) = 58s (+7% from default)
1704MHz (8.5x200) = 56s (+11% from default)
A 1700MHz 400FSB chip would be peform as well as the XP2400+ (2000MHZ/266FSB [15x133]). Unfortunately I cannot run multipliers higher than 13x on my motherboard to verify this.
But to test this theory I lowered the front side bus from 400MHz to 333MHz but raised the multipler from 8.5 to to 11. This results in a speed gain of
133MHz from the 8.5x200 setting. At this setting the calculation is completed in 56 seconds. Thats the same time as the time it took it to complete the calculation at 1704MHz with a 400MHz FSB.
1704MHz (8.5x200) - 56s
1837MHz (11x166) - 56s
So basically an increase in 66MHz, from 333MHz to 400MHz, in the front side bus was equal to 133MHz increase in total CPU speed.
Extrapolating from this conservatively (since an increase from 266MHz to
333MHz is proportionally higher than an increase from 333MHz to 400MHz), an increase in 133MHz on the from side bus, from 266MHz to 400MHz, is equal to a 266MHz increase in total speed.
This is not true for all applications though. Some applications do not take
advantage of the higher front side bus. Games and MS Office applications
generally improve with the higher front side bus speed.
Pros:
1.Gives a significant increase in perfromance in games and office
applications.
2. Does not result in a increase in CPU temperature.
3. No need to increase vcore voltage.
4. Does not result in greater wear and tear on the CPU.
Cons:
1. No increase in other applications like Content creation and DivX encoding.
2. Requires higher speed memory and motherboards that support 333/400MHZ FSB's.
3. Stress on the motherboard and memory is increase and the memory and
northbridge will run hotter shortening memory and motherboard life.
Overclocking 102: How far should you go?
Faster speeds require more vcore. So we are always tempted to raise the vcore and push a bit farther. But how far should you push.
XP2100+ (1733MZ/266FSB) = 115.6fps
Now if we push our XP2100+ to 2000MHz with a 333FSB, we get this:
2005MHz (12x166) = 137.6fps
This is a nice setting. A good 22fps increase at default voltage. Almost all T-Bred "B"s should be able to do this at 1.65v or less, which is within the cores design limit. DLTC's could even do this at 1.5v.
With a 333FSB, you can use cheaper PC2700 and your northbridge wont run too hot.
Now lets max out overclock at default.
2170MHz (11x197) = 153.3fps
Push it further. We need 1.65v to keep this setting stable.
2205MHz (11x200) = 156.5fps
A bit faster, a lot hotter.
Okay lets push further. 1.75v
2315MHz (11x210) = 162.8fps
A bit faster, a lot lot lot hotter.
If your going to overclock your PC, there are five components that are very important. Lets get one thing clear. These are all minimum requirements
You will need a full size ATX case with good cooling characteristics. This should mean that it should have space for at least one 80mm exhaust fan and opening in the lower front (either in the front bezel or the floor of the case) to let air come in. I am surprised at how many generic cases don't have any intakes in front.Plenty of generic cases have this characteristics so I won't bother picking one.
One thing though. About the cases with side exhaust fans. These might cool your CPU better but they disrupt the front to back/ bottom to top air flow which is essential to system (as opposed to CPU cooling). I would avoid them altogether (see below).
The 80 mm fan should be a 0.15 or 0.17a fan. This would spin abot 2500-3000 rpm and move 28-35 CFM of air.
I have seen several generic cases in the market that support two 80mm exhaust fans, and they don't cost more. These would of course be better.
All in all you can get a good case and fan for about P1,500. The requirement for a 80mm exhaust fan is a mandatory requirement for system builders AMD's official design guide, so whether you overclock or not your case should have one.
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Note on exhaust "grills"
A lot of the generic cases in the market have spaces fo exhaust but usually provide many small holes, or worst little slits. These restrict air flow. Even Lian Li better designed stampped grill is less than ideal. What to do, cut it off and put a simple wire grill.
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Side intakes and exhaust fans:
A side intake fan mounted in the middle of the side panel results in poor air flow around the hard drives. Those new 7200 rpm drives get fairly hot. Why is air comes in from the side, less air is sucked in from the front.
A side exhaust fan pulls cool air which comes from the front of the case out, before it ever reaches your CPU.
A side inrake blowing air at you VGA card is a good idea though. If you look at the Cheiftec cases you will see where they out their intake fans. Thats where they should be. Notably these cases have 3 80mm exhasit fans so that even with an intake at th side, they still draw air from the front.
The Lian Li cases and Cooler Masters do not employ side intake and exhaust fans. My advice is avoid, them or at least place them where they can do some good.
Overclocking 103B: What to buy - AMD Heatsink fans
CAK4-88T - This HSF got a lot of good ratings in reviews. But if you will look at these reviews closely, since they are testing the heatsinks and not the fans they replace the fan. With the default variable speed 2800~4000 rpm fan this is a mediocre cooling solution.
Second its a fairly heavy heatsink (625+grams or so), so think twice about this option if yo take your PC to lan parties.
The heatsink though is good. It is copper and is built utilizing the expensive technology. You can place a Thermaltake Smart Case Fan 2 or a 70mm 5600rpm TMD on this unit and it makes it a good overclockers unit.
Another option is to get the 80mm fan on it to run 4000rpm all the time. I understand this can be done by cutting off the thermistor attached to the fan. This require dissambling the heat sink. I HAVE NOT TRIED THIS MYSELF SO IF IT DOES NOT WORK DON'T BLAME ME. Also this will void your warranty.
Cost: P1,800~2,000 (CAK + additional fan) or P1,200 (CAK + void warranty). It hard to recommend since they are now better options.
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Volcano 9 - It looks impressive, and with its 4800rpm 80mm fan it can actually keep up with a CAK4-88T. But than the CAK4-88T is not all that impressive unless modified. I am not recommending this one for overclocking.
P9,000
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Volcano 7+: This was Thermaltatakes top of the line heatsink for a long time. At 6000rpm it is stll competitive with newer heatsinks. It heatsink is also built using skivving technology. It high pitched vacuum cleaner shrill makes it unlikely you will run it at 6000rpm.
Still it does a good job at 4800 rpm (though is still pretty noisy). Running 6000rpm improves tmeps by 0.5~1 degree. I would have recommended this last summer, but there are better options now.
P1,150.
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Volcano 11. This unit has a flaw. Thermaltake abandoned the expensive skivign technology in the Volcano 7+ for the lower xost method of soldering/attaching separate copper fins onto the heatsink. The Volcano 11 while being huge and having a powerful 80mm fan does not perform better than the VOlcano 7+ (@4800rpm). Newer versions might be better.
The grill they put on the fan restrict air flow too much.
P1,400.
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TT Silent Boost
This one looks good. It has a decent sink. WHile TT has not used skivving technology in it they have imporve their soldering. I can't recommend it though because their are better options for the same cost.
P1,450
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TT Volcano 12 Extreme
A budget version of the SLK900A. With a 80mmx80mmx32mm fan and a 60+ fin all copper heatsink, it looks like a monster and performs like one. Most likely you own run it at 4800rpm because the 48db's would be defeaning (also test show that it does not really work better with more the 40-50CFM of air flow). But one running at 3500~4000rpm will be bearable enough.
The shroud supports 70mm and 80mm fans, so if better fans come out you can simply place the stock one which would make an awesome case fan at around 3500 rpm)
Only drawback...LAN Party fans... its all of 725grams.
P1,450
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Aero 7 Lite
It amazing how well this thing does with a CU-AL heatsink and a 20CFM fan. Its 38 or so DB's is more annoying than you thing (sounds like a hair dryer). But it cools almost as well as a Volcano 12 and weighs in at 550 grams.
Drawback. It has a CU-AL combo heatsink so you habve to run it at full speed for it work well. Also, if the blower breaks out of warranty, you can't replace it.
Another drawback is the restat, in some cases it does not fit too well. So it will be recessed.
P1,100
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Aero 7+
When the old Aero 7 had to be recalled, they replaced it with the 7+. The 7+ did not perform as well as the original 7 and is now out performed but it sibling, the 7 Lite, despite having a all copper heatsink. Cant recommend it
P1,650.
RECOMMENDATIONS:
Aero 7 Lite
Volcano 12 Extreme
Right now I would go with the Aero Lite. The Volcano 12 is impressive, but it I am worried about its weight and I do take my PC with from time to time.
Overclocking 103C: AMD Motherboards
With a KT600 you will be limited to the 200~210 range and they really dont cost less the NForce2 boards.
So what board:
Extreme Overclocker: Abit NF7-S Rev. 2 - P6,000 plus RMA problems :) (gotta sed it back to where you bought it).
Watercooler on a budget: EPoX 8RDA Rev. 2.x - P4,750
For the rest of us: Soltek SL-NV400L64 - P3,550
Best buy: Soltek SL-NV400L64
Why? If you are going to spend on a watercooling kit, I recommend you go the Intel route instead 865PE+P IV 2.6C. It would cost about the same and you have a better upgrade path, just make sure you get a Prescott ready board. Even with memory that cannot go 1MHz over 400MHz, you have a good chance at hitting the 3250MHz mark.
It would take an AMD XP3300~XP3500 to match that.
One reason to take the AMD route is to get the best bang for the buck, if you spend a lot I would take the boxed P4 and an Asus 865PE and their 3 year warranties :)
While the articles lean towards overclocking AMD systems, the basics remain the same whether you are using an Intel or AMD rig.
Those who want to overclock are encouraged to read and understand these articles.
Good day and happy overclocking and overclock at your own risk!!!
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