Agree with what Rave said - having the repair person cover the risk means paying a premium for that, and fair enough about the variable resistor, still pence though and insigificant compared to the cost of the work.
BTW, personally I would generally only do this for someone I knew, not people over the net, though I have modded several boards with SMD components without issues.
I totally understand what you mean. I think I will find someone who has done it before in the northwest that comes to the other forum I am a moderator on that way he can trust me and I him as I know a few of the vmodders there. I would be present whilst it be done though.
I just figured out I need a new cpu instead. My 2.8A is an older 533 fsb 1mb cache prescott and it can overclock upto 3.8ghz but it is the cause of the fluctuation in vcore. 3.5ghz is highest stable anything after that the fluctuation gets too far.
So, Does anyone know where I can get a 3.4ghz prescott for socket 478? I cant find them anywhere.
The 533 fsb Prescotts are not 'older' (in fact I think they appeared after the 800fsb ones), they're just designed to offer an upgrade path to people with old motherboards which don't support 800 fsb processors. If you bought a 3.4 it might OC further just because it runs at a faster speed stock, but I think you'll be lucky if it's more than a very small improvement. IC7s are notorious for voltage droop, and you have to remember that they were designed for Northwood processors which use a lot less current anyway. I think spending £20 or so on the mod will be your best bet. It'll cost a lot less than chopping the 2.8 in for a faster processor. Did they even make a 3.4 Prescott in S478?
Small world, I'm in the northwest too (Manchester).Originally Posted by Mesce
The 3.4ghz and 3.2ghz prescott where the the last cpu's that came out for s478 along with the 3.4EE. My 2.8a is 533fsb and has no HT and it is older than these. I compared my droop with 4 other friends that have newer 3.2 and 3.4 ghz prescotts and my droop was far worse than theirs. It is a cpu problem but I can pump up the vcore to allow for stableness in overclock. I dont think I will need the droop mod but I might just get it done anyway. depends how I do overclock wise with newer cpu's. Also i need a 800fsb and HT because it does make that much of a difference.
There's no reason why a 2.8 should droop more than a 3.2 or 3.4; it's a motherboard issue. See if you can try your processor in their board or vice-versa.
As for 800FSB and HT- fair enough I suppose. I would run some benchmarks in apps you actually use before you commit yourself though, you might be surprised how small the difference actually is.
A 2.8 GHz clocked at 3.8 makes sense that it would be causing the voltage to drop if
enough current cannot be supplied. Also if the 3.2 and 3.4 are newer revisions that
could account for the difference in that they have revised core designs etc etc.
2.8/533 = 68.4W
3.2/800 = 82W
3.4/800 - 89W
That's for the 0.13u chips, 90nm run hotter:
3.2/800 = 89W
3.4/800 = 103W
All numbers as per intel spec at stock speeds.
So you'll only be making voltage droop worse with a higher clocked chip.
Mine is a prescott and all prescotts are 90nm. I am on 3.7ghz stable now after increasing vcore enough with my great air cooling to cool it down. Also I plan on getting a 3.2/3.4ghz pressie for also the reason that I can max out my g.skill memory by switching the multiplier too x14 then I will have roughly a 293 fsb over 4ghz and stable.
Rave, one of my friends has the same setup as me with same cpu but with an airconditioning unit inside his pc (dont ask how the fron nozel or something) and he experiences the same droop as me but he can get higher stabel overclock because of the voltage he can put through his prescott because of the cool air around.
What do you need the overclock for? If it's just for the sport of it then it might be alot easier (and cheaper) to just accept what you've got. If you really really want the top 3d mark / pi / sandra score then that's a very long and expensive road...
A 90nm 2.8 dissipates 89W stock, so power/cooling wise it's not much difference if you upgrade. May allow a higher clock for the same power draw and heat due to the higher base frequency.
In that case your money would be better spent on cooling. I agree that you'll need an 800FSB processor to max out your GSkill memory though.
Rich :¬)
The mod above is the standard VMOD, which can be done on just about any mobo.. The chip you need to do it to is used for lots of things so its not a unique mod.
Raising the voltage this way will notremove the droop, but instead raise the min voltage (and keeping the droop). It will also give you more droop, as the added voltage puts the mosfets under higher load.
The problem is the MOSFETs. I expect that they are soldered direct to the mobo, and they do not have any kind of heatsink. Thats the cause. They are at most 87% efficient, so you have a 90w cpu, and 6 mosfets. Thats 3W per mosfet. Now take the almost standard c/w value for TO-220 of about 50c/w, luckly for you that is a bit less, as the mobo is acting as a heatsink so the real value is about 30c/w. Your chips are each about 90c + what ever your ambient is.
Infact thats a bit to close to the thermal limit, so lets assume your mosfets do have a heatsink aswell, but its crap, so you get 25c/w. thats 75c + ambeint.
Get better mosfet cooling, and your droop will go down. The best way to do this, is to buy compleatly new mosfets of exactly the same type, and attach them to a proper heatsinkof about 10c/w or less then solder wires between them and the board. The existing mosfets would need there leads disconnected.
If not, stick some heatsinks on the mosfets, preferably on the underside of the mobo, making sure you do not short anything out. The heat transfers through the mobo better than it will through the package of the chip.
soldering. I can do simple mods, but you will have to pay all postage. I dont really think any soldering is required for this, just better cooling.
Last edited by SilentDeath; 01-02-2005 at 09:48 PM.
SD - I thought most mosfets were rated up to 100c? I'm not arguing with the fact that increased heat = lower efficiency... But surely if there's any noticeable droop at all it's just not a good enough design to deliver the power needed...?
Doesnt matter.. infact its 125c usually... but aswell as that, they still have maximuim ratings. Find out the chips name and search for the datasheet...
Ways to make the design better are more mosfets - so the load is spread between them, better cooling or less load.
The design isnt perfect, but its not going to affect there sales. Improving the design would cost them..so they dont really bother...
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