Why can't I overclock my machine?

[Jack Carr]

I've tried my hand at overclocking my machine and have been unsuccessful. I thought my PC was overclocking material, but it seems that whatever I try to do just makes the PC unstable, it won't boot up. The motherboard's BIOS does allow for manual settings to be applied and even has an overclock on the fly command key, but anything I change just results in my PC going into an endless loop when it tries to boot up.

I'm going to list my system specs in this thread and ask anyone in the know for suggestions.

Thanks in advance for any feedback.

My System:

ABit AN7 Motherboard

AMD Athlon XP 3200+ Processor

2GB Kingston Hyper-X RAM DDR400

BFG Nvidia 7800GS AGP 256MB

Vantec Stealth 520W Power Supply

[Redwolf]

First thing to check is PCI/AGP lock. Must be on.

Then, make sure you set a memory divider first so that you only overclock your CPU and not your memory.

What CPU frequency/volts are you setting when you say it won't boot. And what is "won't book", anyway? No POST?

[Jack Carr]

Originally posted by Redwolf:

First thing to check is PCI/AGP lock. Must be on.

Then, make sure you set a memory divider first so that you only overclock your CPU and not your memory.

What CPU frequency/volts are you setting when you say it won't boot. And what is "won't book", anyway? No POST?

Hi Redwolf,

It seems to go all the way through the boot process and then goes black and starts booting all over again. I had a busy night last night, so I didn't get to check back and see who posted to this thread. I will check that PCI/AGP lock setting this evening.

How do I set a memory divider?

Thanks for your help.

[Schrullenhaft]

Ironically I have this motherboard, but I haven't tried to overclock anything on it as of yet.

The "memory divider" is set from (with the CMOS/BIOS setup) Soft Menu > CPU FSB/DRAM ratio. I'm not sure what the exact settings that are available, but in here you'll specify at what ratio your memory will operate compared to the Front Side Bus. On an AMD Athlon XP 3200+ the FSB will be 200MHz (actual) or possibly denoted as 400MHz (DDR - dual data rate, a doubling of the actual frequency).

Typically you'll have to increase the FSB via the CPU Operating Speed setting to overclock your CPU. Going to the "User Define" setting here will allow you to manually set the External Clock. The Multiplier Factor will typically be locked on most Athlon XP CPUs. If the External Clock is set beyond 200MHz you may need to use something other than "Auto" or "1:1" on the CPU FSB/DRAM ratio setting. However you can overclock your memory too (assuming that your Kingston HyperX can handle it) by keeping the setting on "Auto". However you may need to adjust the memory timings a bit 'looser' (higher latencies, etc.) in order for the memory to operate at a higher clock speed. The memory timings are set from Advanced Chipset Features > Memory Timings. Setting this to "Expert" allows you to manually set the parameters (higher values are less performance, but may be necessary for overclocking). Using the CPU FSB/DRAM ratio allows you to keep the memory clock at 200MHz (or possibly lower, depending on what you use for your External Clock). Using a "5:4" ratio should allow you to have an FSB of 250MHz while keeping the memory operating at 200MHz (if I recall this correctly).

Overclocking your CPU will also require (according to the motherboard documentation) that you have the CPU Interface setting set to "Enabled" in order to use the 'overclocking' settings.

You'll also want to probably keep your AGP Frequency set to "66MHz" for the most stable operation. Some videocards can take higher AGP frequencies (which can boost performance sometimes), but quite a few other cards become unstable with anything over the standard 66MHz. To my knowledge this setting also acts as the "PCI/AGP Lock" that Redwolf mentioned since the PCI clock will probably remain at 33MHz (the standard) if the AGP clock is set to 66MHz (AGP is actually the PCI bus doubled, if I recall correctly). If you increase the AGP Frequency, the PCI frequency will also increase, possibly causing problems for any PCI devices (including SATA drives).

The Power Supply Controller portion will possibly need to be set to "User Define". This will allow you to change the voltages for CPU Core Voltage, DDR SDRAM Voltage, NB Core Voltage (north bridge - the memory controller) and AGP Voltage. For overclocking the CPU you may need to increase the voltage for the CPU and possibly the north bridge. If you overclock the RAM (using the "Auto" or "1:1" settings) it may require increasing the DDR SDRAM voltage too. If you decide to use a higher AGP frequency then possibly increasing the AGP voltage may be necessary, but probably not recommended.

Any changes to the voltages listed in the BIOS should be done carefully and in small increments. Increasing the voltage essentially increases the "wear and tear" on the electronic components and may reduce their life span (and also cause them to heat up to higher temps). But the increased voltages can result in increased stability when you overclock. There isn't an absolute correlation between higher voltages and higher overclocks/stability, but higher overclocks will probably need more voltage. Using too high of a voltage can permanently damage some components and that is why care must be used when making these changes. You may want to do some web searches on the success others have had overclocking the XP 3200+ CPUs and what voltage settings they may have used (keep in mind if they are using air or water cooling though).

To immediately apply some of these changes for overclocking, you can press <F8>. Hopefully things act stably at this point, but you probably won't be able to tell until using Windows, benchmarks and 3D games to tell for sure. One common test (assuming you boot into Windows safely) is Prime 95 used in conjunction with SP2004 "Orthos" (install Prime 95 first). Prime 95 actually calculates Prime numbers, while the SP2004 software acts as an easy interface to tell you if there are errors and how long you've been running. This should give you a fairly good idea of your CPU and memory stability if you run them long enough. This may require quite a few hours of testing to make sure that an overclock is 'stable' (sometimes 24 or more hours).

Here's one Overclocking Guide (Neoseeker) and there are plenty of others you can find on the 'net. This guide isn't overly detailed, but it is a fairly decent introduction to overclocking.

In your particular case here you may need to increase the CPU voltage and north bridge voltage a little and possibly decrease the amount of overclock you've applied. It takes a lot of experimentation to find a reliable overclock.

[ February 20, 2007, 11:16 AM: Message edited by: Schrullenhaft ]

[Jack Carr]

Wow! I've got my work cut out for me. I'm going to give this a try over the weekend and see what I can do.

Thanks, Schrullenhaft, for the information.

[Jack Carr]

You guys are the best! I'm overclocked! Ha ha!

The first time I tried doing this, I was messing with the multiplier factors. I left that setting alone and just unlocked the settings and upped the voltages.

Schrullenhaft - Your directions worked great. Thanks so much. I'll see how the machine runs for awhile with the increased voltages, but so far so good.

[Redwolf]

What kind of testing did you do for the new clocks?

You realize that an untested overclock can and probably will scramble the contents of your harddrive(s)?

[Jack Carr]

Originally posted by Redwolf:

What kind of testing did you do for the new clocks?

You realize that an untested overclock can and probably will scramble the contents of your harddrive(s)?

Nope, didn't know that. What sort of testing would you recommend?

[Redwolf]

36 hours of mprime (prime95)

24 hours of memtest86+

SuperPi 32M a couple of times

(google will find the downloads)

You need to record you room temperature and later monitor it, as the above procedure only certified the overclock for your current temperature (obviously). In general you want to crank up heating in that room to the highest it will get in summer for the duration of this test, so that you can forget about it later.

[Jack Carr]

Originally posted by Redwolf:

36 hours of mprime (prime95)

24 hours of memtest86+

SuperPi 32M a couple of times

(google will find the downloads)

You need to record you room temperature and later monitor it, as the above procedure only certified the overclock for your current temperature (obviously). In general you want to crank up heating in that room to the highest it will get in summer for the duration of this test, so that you can forget about it later.

Thanks, Redwolf. I'll give this a go. With TOW and CMSF on the horizon, my processor needs a boost.