"Paul - Home Pc" said:
Hi
I cant seem to get my PC to run fast - its locked at thinking i got an
AthlonXP 1500+.
Got a 2400+ Semperon installed - flashed the bios at 1015 release.
Can mixed speed DDR memeory be a problem?
Any Ideas?
P
http://www.tomshardware.com/cpu/20040728/sempron-01.html
Says Sempron 2400+ is 10x166. Make sure the CPU clock is set to
166MHz and then it will be running at its full speed. 166MHz
CPU clock gives FSB333 for the front side bus, and works best
with DDR333 transfer rate on the DRAM.
With mixed speed DDR, the BIOS will pick the slowest DIMM and
use the timing info from it, to define operation of the
whole memory bus.
The other issue, is what dividers are available, between CPU
clock and memory clock. Item 2 in section 1.4.2 of the user
manual, tells you what combinations are available. With
FSB266, you can run DDR266, DDR333, DDR400. With FSB333
(which is what your processor has got), you can run DDR333
or DDR400. So, if you had a stick of DDR266 memory mixed in
there, then you'll be stuck with FSB266, unless you overclock
the memory. That would require setting memory timing manually,
using relaxed timing numbers for the RAM (i.e. if the RAM was
CAS2, you would run it at CAS2.5 or CAS3, setting the other
timing numbers to higher numbers as well).
Item 3 in the same section of the user manual, says "PC2700
two sticks of RAM max", so if you have three sticks of RAM
mixed together, you are pushing your luck. Some BIOS
automatically enforce reduced RAM clock speed, when they
detect a quantity of RAM that isn't likely to work at that
speed. Your best hope there, is to experiment with manual
timing, and if the RAM still gives a lot of errors, dump
two of the sticks, and buy a 512MB or 1GB double sided DIMM
to replace them. If you want to buy a 1GB DDR DIMM, to
replace some other sticks, buy it from a reputable supplier
like Kingston or Crucial, as they won't sell you a DIMM
constructed of "stacked" chips. Many of the generic 1GB
DIMMs you find in Pricewatch, will be stacked construction,
and that means the DIMM has twice the bus load of an
ordinary double sided DIMM, and that will guarantee the
bus will not run at full speed. (I call those "restocking
fee DIMMs", because the unsuspecting buyer, ends up returning
the memory, and giving the vendor a "restocking fee
HTH,
Paul
