Why does overclock result in slower performance?

[magelan_2000]

I got myself a new (green slab) AMD XP 1800+ to overclock on my KG7-Raid.

When running on designed speed there are no problems.
As soon as I overclock the CPU to 1900+ or 2000+ level I get an immediate performace drop. Windows XP makes no erros an doesn't crash out. I used both Prime95 and Seti@home to burn CPU but they produce no errors whilst taking longer time to complete units as compared to before CPU was overclocked.

I am completely puzzled here! MOBO recognises the CPU as higher clocked one (CPU unlock is successful) but what the hell?!
I use watercooling and temperature never gets above 49C at full load at any speed.

Any ideas?

[sohailm6]

How are you overclocking, FSB, Multiplyer or both ????? Also I would try Sandra for testing performance at stock and overclocked speed.

Sohailm6

[magelan_2000]

I used only multiplier to overclock.

[joek71]

I also have KG7-Raid with AthlonXP1500+ @ 1.616Ghz XP1900+, What are your BIOS settings? Does only Windows lruns slow or does it load slow? What is your RAM and what are the settings for it?

[magelan_2000]

BIOS is set on its standart Optimal settings. RAM is 2x 256mb Crucial DDR PC2100 Set at default Optimal BIOS setting.

Windows is not really slower but CPU hungry progs like PRIME95 or SETI are slower by 20%.

May I ask another thing? Do you prop-up voltage for AMD XP or not? In technical data all Athlons XP run at the same voltage. Do they in the overclocking world?

[Tasuke [H]]

Prime95 and Seti are not CPU bound. They are mostly Memory bound. Your stick of ram may have gone to the less aggressive timings if you set to optimal. Check that the ram timings are not set from SPD. Set them manually.

Also, run the Sandra mem and cpu bench.

If the mem bench is fine and the CPU looks slow, that is one thing, but I bet that the memory bench may be on the slow side, and the processor is just fine.

[joek71]

AthlonXP like higher volts, I modded mine, it is currently at 2.06v. Do the ram manual, here is a link to it:
http://www.icronticforums.com/showthread.php?s=&threadid=14563

Let me know how it is going.

Good luck,

[magelan_2000]

Do you have RAM coolers (as suggested in that guide)?

[joek71]

This is the Ram I have:
http://www.mushkin.com/cgi-bin/Mushkin.filereader?3cf43e9d0c27b2722741c0a80102067 f+EN/products/990856

it comes with heat spreaders. If you want to purchase something for your ram go here:

http://www.coolerguys.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=001&Product_Code=SMH-ACT-MEMCOOL&Category_Code=CPC-ChP

but I am not sure if it will fit PC2100 DDRam, find out call the company.

Good luck,

[Farabomb]

Yes the heat spreader will work on pc2100. I have the passive ones on mine. They work quite well and I don't know if the fan really does that much.

[joek71]

I dont have that also, mine came with heat spreaders. I was thinking of getting it but dint think of it much since mine came with it. Maybe if mine next ones wont come with it i will get that heat spread.

[bldegle2]

x's don't make much difference in 'puting power at the speeds we are talking about, BUT,



unlockage and a FSB of 166 and above can bring a smile to most who take the extra effort.

go for it.

baldy:cool: