cpu speed, ram speed or timings? which to head for??

matt100 · 29 Jun 2006 at 08:25

Right, started overclocking my shuttle.. its a watercooled sn25p with an x2 3800 and 2gb of ocz platinum 3200.

I stuck the ram on a 133 divider and I've managed to get the cpu up to 2.8 with 1.5v but I'm really not interested in running it on the edge, did that with phase and I just want a solid reliable clock now.

So I've settled at 2.6ish which takes 1.4v (although not fully tested stability here so it might need a bit more) that sets the ram at 173mhz 2-3-2-5. Tested it with a 166 divider and it didn't want to know, that would be 215mhz for the record.

Options..

1) drop the cpu clock to 2.4 with the memory on 166 which would hit it at 200mhz on the nose and retain the 2-3-2-5

2) keep the clock and keep the memory on 133 which means its at 173mhz 2-3-2-5

3) keep the clock and drop the latency, I have no doubts this ram will do 215mhz at something like 2.5-3-3-6 or similar.

Opinions?

turbotoaster · 29 Jun 2006 at 08:31

what volts were you giving the memory, ya could try more volts on them, the thing to do is find the highest mem clock you can get, use sandra mem bandwith tester to check each time u change it.

once you find your highest mest with the fsb and multis to find the closest to both

matt100 · 29 Jun 2006 at 08:33

I'm really not that bothered for getting that far into it, I suppose I could try more voltage but for a 2gb kit 215mhz cas2 is quite an effort iirc.

ted34 · 29 Jun 2006 at 08:34

Can you get 1:1 with 2.5 timings? If not then id go for the 215 with 2.5 timings as 173 is fairly low. Normally id say go for cas2 but id try and keep that above 200mhz or thereabouts. Have you run any benchmarks at different settings?

matt100 · 29 Jun 2006 at 08:40

lol.. no benchmarks..

tbh after running this 3800 at 3.2 under phase with sli'ed 7800gtxs and benching the hell out of it I don't really see the point benching this.. I like big numbers

I know I should to see what the best option is but I don't have the time so I thought I'd cop out and ask the experts!

I'll give 2.5-3-3-6 a whirl and see what happens.

matt100 · 29 Jun 2006 at 08:50

well this is about as scientific as you're likely to get from me..

1mb superpi run..

2.5-3-3-8 216mhz = 33.391s
2-3-2-5 173mhz= 34.203s

so actually quite a large difference considering it picked up a second in that short test. I'd expect to have to pull out at least another 100mhz on the cpu to achieve the same effect, probably more.

p4radox · 29 Jun 2006 at 09:52

matt100 said:
well this is about as scientific as you're likely to get from me..

1mb superpi run..

2.5-3-3-8 216mhz = 33.391s
2-3-2-5 173mhz= 34.203s

so actually quite a large difference considering it picked up a second in that short test. I'd expect to have to pull out at least another 100mhz on the cpu to achieve the same effect, probably more.

That's what I'd expect. I had a similar conundrum with my Opty and some Crucial value ram - on a low divider I could push the CPU further with the RAM on tight timings, but the ram was at something like 176MHz. I dropped the CPU speed a bit and opted for the higher divider which put the ram around 200 but with slacker timings and found it to take about a second of my Pi time.

All these people who say CPU speed is more important than anything else on A64 should try it sometime!

(I know it's true on the larger scale)

SiriusB · 29 Jun 2006 at 14:22

I have the same OCZ Platinum RAM and from HOURS of testing I can tell you that at the stock timings that RAM is going nowhere past 215MHz.

To get my OC of 2.6GHz on my 4400+ I had to fiddle around with the CPU Multi and HT values to get 2.6GHz with a higher HT. Reason for this was none of the dividers let the RAM run at 200MHz. It was either far too low or too high.

Get yourself a pen and paper out and lower the CPU multi and raise the HT and then you should be able to use a divider that works well

SiriusB

matt100 · 29 Jun 2006 at 14:26

there's no point, if I go for 9x280 for 2.6 the ram would be at 190 on a 166 divider, the next one down is 325x8 and the fsb on my shuttle only goes to 300.

I'm happy with 216 2.5-3-3-8 tbh. It'll do for me and it seems rock solid. Been priming since this morning and I normally only need 30 minutes to convince me its stable enough for my needs.

ted34 · 29 Jun 2006 at 14:34

Generally you need about 60mhz extra on ram speed to justify going to cas2.5 over cas2 but as you were running ram so slow at 173 it must have had a bigger impact.