Overclocking Oddities

[warhorse]

As you probably know by now, I have a T-bird 800 on a KT7. At 8x100 I have 40-45c temps. Cool. I figure drop the multiplier, up the bus. Based on temps I can' overclock too much so Ill go for more bus. 108x7.5=810... and temps went to 55c... 10mhz and 10c more. At 805mhz, the temps are the 40-45 again.. this isn't logical... maybe my RAM can't take it?

Also, I have it running at CAS 2. That may be it. My question here is, if I go to cas 3, how many mhz do I have to go up in order to make up for the latency?

Oddly enough, It boosted my Sandra Mem Benchmarks from 376/406 to 402/438 which puts me AHEAD of all the comparison scores! Yess!! Finally!

In all my tweaking I've gone from 306/343 to 402/438! Now all I need is some PC133 so I can go from 107mhz bus to 133.. 6.0x133 would be sweet

[This message has been edited by warhorse (edited 08-26-2000).]

[grover]

Well, to truely make up for the extra clock cycle latency, you'd have to go another 50% faster... but then your RAM would have to meet the CAS2 performance which it clearly can't, and that kinda defeats the purpose of what you're trying to do, heh.


At any rate, CAS2 doesn't offer a while lot of performance over CAS3. It just gets the information to your CPU in 3 clock cycles instead of 2 clock cycles- the RAM is still capable of fetching 100 million chunks of info per second, CAS is just the delay between CPU requesting and being given it. You're only losing probably an avg 2% mem speed, to a max of 15% in applications that can really take advantage of it. Try it both ways and BM it in Sandra, SETI, Quake3, or whatever you put the highest performance priority on and see how it really affects you

So, umm... if you can get another 5MHz out of your RAM running at CAS3, it's probably worth it.

[This message has been edited by grover (edited 08-26-2000).]

[warhorse]

I did some math and about 6mhz makes up for the cas change... I took it down to cas3, and upped the bus to 117 and dropped the multiplier to 6.5=805mhz. My scores went up 10/11.

Chart:

100mhz interleaving 0 way cas3= 306/343
100mhz interleaving 4 way cas3= 357/389
100mhz interleaving 4 way cas2= 376/406
107mhz interleaving 4 way cas2= 402/438
117mhz interleaving 4 way cas3= 412/449

Increase of 106/106
Increase of 34.64%/30.90%

The multiplier was adjusted to keep it around 800mhz. I can't go higher due to heat. Therefore I can't up the bus more or drop the multiplier more because it won't complete the mem test at 6.5x123

[This message has been edited by warhorse (edited 08-26-2000).]

[This message has been edited by warhorse (edited 08-26-2000).]