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nice link deception`` intresting read so far
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Gregory_WE said:What I'm gathering is if your RAM speed is still the same synch and asynch, the performance would be virtually the same - which is what I was specifically wondering about. Obviously, a system at 300 1:1 will be faster than a system at 300 5:6.
Gautam said:There are two facets to this "debate" which I believe is causing this confusion.
Firstly, does using a divider explicitly decrease performance? No.
What I mean is, is 9x305 with a 166 ( CPU/11) divider slower than 11x250 "1:1" (200MHz or CPU/11 divider) ? The answer is no.
Using a different set of multipliers with dividers nets you the same performance as long as the memory speed remains constant
Does running memory slower take a performance hit? Of course it does.
When people say that dividers take no performance hit, it resonates with older platforms (P4, AXP...) that had an explicit latency increase simply by using a divider, which the A64 does not have.
Bottom line, run your memory as fast as you can, using any possible combo. Which combo of multipliers and dividers it is doesn't matter, just like Gregory said.
Comparing the first two columns it would seem to indicate the the one with the 5:6 divider runs better performance wise than the one running 1:1 - this despite having a LOWER ram frequency!! The problem however is that the memory timings differ and also one is at 1T whereas the 1:1 is at 2T so this comparison does not really have any basis quite frankly and should reallybe ignored.deception`` said:Sorry, but anyone who thinks that there is no performance penalty for using dividers is flat out wrong. While it is nowhere near as significant as on an Athlon XP system, performance differences do in fact exist. Here's a good article that should clear everything up:
http://www.insanetek.com/index.php?page=overclocka64
deception``
glock19owner said:OC Dect:
If you know of a good way to run a 3200 like you stated with the 3500 above...let me know and I will rum some benchmarks with latency test included...
OC Detective said:Simple way to prove it is to get someone to test a 3500+ run it at 229 x 11 at 1:1 and 280 x 9 at 5:6 that way the cpu and ram frequencies are virtually identical and if running async does give a performance hit then it would show up in benchmarks.
Not neccesarraly true. On A64s higher multis also net better bandwith. So overall its about balance just like it was back in the AXP daysGregory_WE said:What I'm gathering is if your RAM speed is still the same synch and asynch, the performance would be virtually the same - which is what I was specifically wondering about. Obviously, a system at 300 1:1 will be faster than a system at 300 5:6.
Overclocker550 said:That is not a fair comparsion because the fsb are different. Of course they would perform viturally the same because the cpu and bandwith end up about the same, however try running 266x9 1:1 and 266x9 with "166" divider, youll lose alot of ram bandwith and performance. This is what im trying to say that async takes a big performance hit where youd need 150MHz higher cpu clocks to make up for the loss of ram bandwith.
"First up 10 x 200 at 1:1, then at 8 x 250 with a 5:6 divider on (RAM:HTT). That way both cpus are at 2GHz and the ram frequencies are both 200Mhz. That would clear it up once and for all - but remember for it to be statistically significant it would have to exceed the limits of error (whatever they are in the likes of 3DM01 etc)."
once again, HTT doesnt matter, cpu clocks are equal and ram bandwith is equal. However 250x8 1:1 would crush 200x10 1:1. Take my case, 262x9 1:1 is about as fast as 280x9 with 166 divider. What happened there? My ram bandwith decreased because running async lowered my final ram MHz below 262. If there was a divider where I could run 280x9 with the ram at 262 then yes it would have the same ram bandwith as 262x9 but the extra cpu MHz would pull me quite ahead. Problem is, there is only a handful of dividers, mine has 100, 133, 166 and 200. some mobos have a 183 but NOT mine!
Other than the multi issue yea. The main vice for A64s is the multiplier. I forget exactally why but there is a sizable bandwith increase with a higher multiplier. Almost identical to the hit taken by going asynch on an AXP.OC Detective said:The whole point of this thread was when the cpu and RAM were the same does the divider have an inpact (as it would on NF2's). The answer is seemingly no!
afaik and im being serious, might have to dig up the article it is true. Here is basically how it went.OC Detective said:Sentential if that were true then you would see a difference in the two options I showed for the 3200 and 3500+ correct?
For 3200 that would mean 10 x 200 (1:1) being better than 8 x 250 (5:6). After all the only way you can compare them correctly is so that the cpu and RAM frequencies are the same is to have a lower HTT on the higher multi.
hitechjb1 said:Possible explanation:
When the CPU is clocked faster (consuming faster), the memory controller is not fast enough to keep pace and provide enough data I/O with the L2 cache running in sync with the processor clock, hence resulting in more cache wait states relative to the memory controller and in turn lower efficiency (the actual bandwidth is still higher, but efficiency which is bandwidth per memory clock is reduced).
Will the revision E0 correct/improve this?
Miguita said:On the platform in question though, one has the option of adjusting the memory speed and HTT independently of each other, without losing performance due to latencies, as the RAM doesn't use the HTT. I'm not saying one should lower the memory speed just for fun. But if the memory cannot run as fast as the HTT, it can be adjusted so that it still runs stable, without losing performance due to the latency-issues that are seen on platforms that have an FSB. Thus allowing higher CPU-clock (on a locked CPU). And again, there is no such thing as "running in sync" with A64s.
The "latency issue" I was referring to, has nothing to do with the timings that can be adjusted in the BIOS (like CAS, tRP, etc). Those could be the same in both scenarios. What I meant was that the memory controller on an A64 will communicate equally efficient with the RAM, no matter the HTT / MEM-ratio. Lowering the ratio is a good idea if your memory is holding back the CPU while using the 200-ratio. And besides, if your CPU / cooler makes it possible to OC further, 320 HTT would certainly be better than 275.glock19owner said:So Based on what you just stated...how is running at say, 320FSB/HT with 5:6 divider and 3x HT be faster/equal then running like my setup at 275 1:1 with 4x HT and tighter timings...