How to: Find the Limits of my CPU, Memory and Motherboard? - A Quick Guide. - Overclock.net

*ncsa* · 07-01-05

We all want to find the maximium our systems will go and how far we can OC. That's why we are here and the fun of it but we get frustrated because a particular setting or change didn't have the effect we thought it would and we cannot work out why.

So here is a very quick guide to help you discover the walls or boundries which should help you know what to change and when, be this a hardware change or a BIOS setting. This is by no means a definitive guide but should get you to a point more quickly where you can then fine tune your system and play in more detail.

So what are the key walls within the system:

1. Motherboard HTT
2. CPU speed
3. Memory Speed

NOTE: The HTT multi should always be set to ensure that the FSB x HTT multi < 1000Mhz (800Mhz for some CPUs or chipsets)
200 = x5
< 250 = x4
< 333 = x3
< 400 = x2.5 / 2

Quote:

How to find your max HTT speed
Lower your Cpu multi to 6 or 7.
Set memory to 100 (1:2 / DDR200)
Set LDT / Chipset voltages to max, if these options are available
Increase your HTT/FSB and boot your computer until it fails to boot. Back Down 2-3 Mhz till able to boot. This is your max HTT. Multiply your Max HTT by 0.95. Write this number down. Example 342 x 0.95 = 324.9 Round it to 325.

How to find your max CPU speed
Set your cpu fan to kick on at 30C or as early as possible.
Set your Cpu muilti to Highest 9,10 or whatever.
Memory speed to 100 (1:2 / DDR200)
Set Vcore to 1.6 - 1.7. 1.6 for air 1.7 for water cooling, higher if you know the temps will be OK under load.
Raise HTT till you fail to prime for 5 min. You only need to pass for 5 min for right now. When you fail lower HTT by 3-5 Mhz and try again. This is your max Cpu speed. Multiply it by 0.95. Example 2700 x 0.95 = 2565. Write this number down.

How to find your max Memory speed.
Memory speed to 200 (1:1 / DDR400)
Give your memory between 2.9 - 3.4 volts depending on what type it is.
Set CPU to 6-7 Multiplier.
Raise your HTT till you fail mem test 5-6. You can select for Memtest to do one pass on test 5 and one pass on test 6. When it fails Muiltiply by 0.95. Example 250 x 0.95 = 237.5 Round to 238. Right this number down.

Then put all those numbers into Gogars Athlon 64 Optimizer found HERE
Use the settings from the top rown down. You do not have to change anything in the importance weighting. Also put 1000 into the Ht box.

Some have already seen this and even if you do not run through the steps, the Gogars tool will at least give you a quick way to see what is needed to to get that OC you are after. And as you will find it shows a range of options that maybe the 1:1 ratio is not always the best.

So try it out and hope it works well for you as it has done for me. :D

EDIT:

Added Gogar's A64 OC Optimizer Chart.

Quote:

Fields in red are where the A64 produces different memory speeds than expected from the formula cpuspeed/ceil(multi*200/memclk)

**The Duke** · 07-10-05

Thanks ... I'v been following your posts and progress.
Nice write up ... very to the point!

**Krunk_Kracker** · 07-10-05

Excellent write-up!

*ncsa* · 07-13-05

Thanks .. it is a simple tool and if used will help get a quick start on where to look for their particular wall. I do like the Gogars tool which has now been updated to cater for the additonal divider options.

*ncsa* · 07-24-05

Updated and added another useful chart for the A64

mikester · 09-04-05

This guide is great, but when I tried it I noticed one thing. Following the instructions exactly, I was only able to raise my HTT to 250. From other posts I've read, that is pretty much the limit of the memory controller without raising the voltage (which is omitted in the guide). Without raising the voltage, the HTT speed is going to be the limiting factor on most overclocks.

Akkarin · 09-08-05

what is the ratio for memory limit supposed to be set at?

*ncsa* · 09-08-05

@mikester - good point, added to increase LDT / Chipset voltages if supported by the MB, as these will allow you to push further.

@ Akkarin - good point, an assumption that was not clear, this is DDR400 or 1:1 ratio - added this to the settings

Thanks

EDIT:

Added HTT settings for various FSB settings

Akkarin · 09-08-05

one last point, LDT mult can be the limiting factor, it should be set to about 3 to avoid mobo damage due to a FSB that is ocd too high for the mobo (ex. over 2000 - quite easy to due on my 3200+ venice with the default being 5x LDT)

mikester · 10-05-05

Yes, I think the HT multi was limiting my overclock. When I dropped it to 3x, I was able to get the FSB over 300 without raising the chipset voltage.

Thanks again for the great guide!

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How to: Find the Limits of my CPU, Memory and Motherboard? - A Quick Guide.

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