MDD 1.25 single PLL & CV resistors location

[blacksheep]

Hi all forum members,
I've been googling for this long time with no luck. So i decided to figure it out by myself (even if i'm a electronics noob ). With PLL position it was very easy - they are described at the front of PCB, on the right. Only difference was the PLL4, so i thought that is equal to PLL_EXT, and i was right PLL's config table is exactly the same like DP modules on bitsandpieces.info. Little harder was CV resistors location. I compared resistors around voltage regulator on MDD's 867 DP daughtercard (which have the same voltage regulator like my single 1.25 and 1.25 DP 2 MB L3 - LTC1709EG). Voltage table is also exact like 1.25 DP 2 MB L3 CPU. I have found adequate resistors on my 1.25 single module and quickly OC'ed it to 1.67 GHz with 1.65V with no troubles. It is fully stable, i had run few Xbench and Cinebench 2003 test, net surfing etc without hangs or kernel panics. I have tried 1.75 GHz at 1.65V but my MDD freezes when gets about 40 degs C (weird, at 1.67 GHz with R9800 + 2 HDDs on board it gets about 49 degs C, and no freezes or other issues) and i got Kernel Panic once at startup. I bumped voltage to 1.7 and then 1.75V with no luck - it freezes even faster than at 1.65V, before it gets 30 degs C. I'm thinking that the problem is in cache chips. Now i'm back to 1.67 GHz and still it runs stable with no issues (i'm writing this post from this MDD). I will try to lower voltage to 1.60V, to get lower temp. My CPU is 7455B v3.3 at the 820-1497-A board. Stock Core Voltage is 1.55V (01010). I put it on FW800 1.42 DP's logic board for testing, because i bought this CPU with "dead" lobo. I have uploaded pics of resistors position and screenshots to Imageshack.


I have tested voltages: 1.55, 1.65, 1.7, 1.75V – others are untested yet. I have posted my Xbench 1.3 results at 1.67 GHz to Xbench comparison page: db.xbench.com/merge.xhtml?doc1=341913&doc2=1&setCookie=true
P.S. Owca666 is free polish translation of my nick "blacksheep"

Regards
blacksheep

[originalmacnut]

Gratz That's a nice OC you got going there, 30C isn't to bad, MDD run hot anyways, unless your name is Aqua, lol.

[B B]

Is that youre looking for ? this

[blacksheep]

I know this article, but this is for Dual modules only, look at my pics, single CPUs have different resistors location (and they are described with different numbers). Like i wrote before, PLLs location was easy to find, little harder was to identify CV resistors. Tables are the same for single and Dual CPU. Michiro Isobe's and bitsandpieces knowledge was the base of my mods, but there is no info or about single CPU daughtercards. BTW, i have OC'ed few Duals with no problems, but single was the challenge.

Update:
I lowered CV to 1.60V and it runs fine and stable with temps lower by 3 degs C.

[timyjl]

Thanks blacksheep for all the info. I tried this OC on my MDD '03. @1667 & 1.6V it boots fine but crashed after a few minutes at around 35°C. I increased core voltage to 1.65V and got a kernel panic at startup. I settled for 1.5Ghz & 1.55V. It runs great with temps ranging from 29°C @ idle 34°C – 38°C lite to moderate load and toping out @ 42°C during a Cinabench R10 render test.

Overall not a very noticeable performance improvement but still pretty cool.

As an added bonus I greatly improved my soldering skills.

Thanks again.

[abrax]

Hi guys,

What about the cache? Did You change the soft to make it run faster?

I've read somewhere there that the cache won't allow the processor to go faster even if it could handle it.

?

[timyjl]

No mods to the cache. I didn't find any relevant info on it from a cursory googling either.

Do you remember where you read that?

Edit: Found it, I think. Seems you need Powerlogix CPU Director which only works thru 10.4.9
to change cache settings.

[reddrag0n]

Well, tried some of these settings in my SP 1.25 MDD...

1.5 GHz with the default voltage of 1.55 works.
1.67 GHz with 1.65 voltage doesn't bong, and the fans ramp up to high.

I think i will stick to the safe 1.5 GHz.... ;D

[blacksheep]

Try 1.58 maybe... but +250 MHz it's 20% more than stock, so it's good too

[reddrag0n]

what would be a safe voltage to run that on 1.58 ghz?

[blacksheep]

Start with stock and bump one step up if needed. 1.6V should do, IMO going higher for +80 MHz is not worth it (heat wise).

[reddrag0n]

Well, went with what you said and bumped up the CPU. Was running at 1.5 GHz @ 1.55v, now am sitting at 1.58 GHz @ 1.55v. Seems stable enough. The temperature is now sitting around 40℃, unlike the 30 to 35℃ at 1.5 GHz.

Oh well, my new fans are up to the challenge.

Anyways, here are some benchmark results. (take into account that i am still running my ATI Rage Pro card)

Running at 1.5 GHz @ 1.55v




Now these are the scores running 1.58 GHz @ 1.55v.

[aquamac]

X bench responded well with the 1.5 - 1.58 GHz step-up!

[reddrag0n]

Actually, Geekbench raised 8 points, Xbench lowered 1.62 points.

OpenMark, not going to try with the Rage. Even with the Tiger ATI drivers, OpenGL is nonexistent.

[aquamac]

Sorry, my bad, meant Geekbench. you need that GFX card!