Overclock&OverVolt?

[85kimeruccio]

è ovvio ke è diverso.. la resistenza e la potenza dissipante è diversa..

le temp sono diverse ovviamente..

ma la VELOCITA in cui la temp sale puo essere diversa da wb a wb

[bemauri]

ma, allora, qual'è il momento "giusto" per passare all'acqua? a questo punto io direi quando ci si accorge che il proprio potenziale di crescita è impedito dalle temperature; ovviamente dopo aver accertato di avere per le mani un buon complesso cpu+ram+mobo ancora in grado di crescere ma in pericolo (parlo per la cpu) d'arrosto; oppure no?

.....mi viene il dubbio di essere un po' o.t. ...nel caso me ne scuso con la comunità.

[85kimeruccio]

beh.. passare ad un sistema a liquido porta molti vantaggi.. non solo riferito all'overclock..

ma temprature.. rumore.. staffa al soket infinita.. ecc ecc.. oltre al mitico fattore figosità

[MORETTOSA]

io sono passato a liquido puramente per il rumore adesso non ho ventole nel case con una temperatura accettabile sulla cpu 35 idle 43 load

[CaberNET54]

Tornando a bomba sulla questione "Overclock daily-use" e VCore, io ora viaggio quotidianamente con 1,8 di Vcore 251x9,5 - 2390 Mhz stabili (40C. Idle - 50C. Full load) , che per un 2500 Mobile, corrispondono circa ai voltaggi necessari per un 2600 Mobile per viaggiare a 2500 Mhz circa (per alcuni proci fortunati forse un po' di più).
So che sono parecchi, però ho cercato di informarmi e ho verificato che non sono impostazioni suicide ma sufficientemente adeguate per garantire una vita media per il processore (statisticamente parlando) di circa 7 anni contro i 10 (sempre teorici).

Qui di seguito riporto un breve estratto preso da un forum in inglese, che ho trovato molto interessante (posso inviare il link per il thread completo solo in privato!).


Ringrazio hitechjb1 per il testo che segue, di cui è autore:

......"Effect of high Vcore and electromigration on expected failure time for Tbred B/Barton

In the last post, I estimated and related the CPU over voltage with expected 50% sample failure time (life expectancy) based on electromigration emprical results (Black's equation). Here put them into numbers for CPU voltages.

Statistically, for the same level of temperature specification,
A 10% increase in Vcore, would shorten the failure time to 83% of nominal failure time.
A 20% increase in Vcore, would shorten the failure time to 69% of nominal failure time.
A 30% increase in Vcore, would shorten the failure time to 59% of nominal failure time.
A 50% increase in Vcore, would shorten the failure time to 44% of nominal failure time.

So a 30% increase of Vcore reduces the 50% sample failure time to 59%. 30% over stock voltage for Tbred B/Barton are
- 1.95 V for DLT3C, such as the famous Tbred B 1700+/1800+
- 2.08 V for DUT3C, such as the popular 2100+
- 2.15 V for DKT3C, such as the Barton 2500+ or higher.

E.g. If the nominal CPU life expectancy is 10 years, for Tbred B DLT3C
- 30% overvolt to 1.95 V, the number would be down to about 6 years (59%).
- 20% overvolt to 1.80 V, the number would be down to about 7 years (69%).
- 10% overvolt to 1.65 V, the number would be down to about 8.3 years (83%).

They seem to fit nicely w/ the AMD absolute rating 2.05, 2.15 and 2.20 V on Vcore for the DLT3C, DUT3C and DKT3C respectively. Max Vcore for Tbred B and Barton (page 5)


Based on the analysis, we can rule out the guessing numbers of 1.8 - 2.0 - 2.2 V for max Vcore flowing around and also the concern of failure within weeks or months.

As far as temperature to not having additional adverse effect on chip behavior from electromigration on top of voltage, it should be below the max temperature rating of 85/90 C (for TBred B/Barton). So using a temperature cap of 65-70 C is reasonable, since above which most CPU would be overclocked above the break-even point of 10 MHz/C for Tbred B and Barton. Further increase in voltage and temperature beyond 30% and 65 C, even if it is stable, one would get very little return in MHz, but greatly shortening the expected failure time. (Besides temperature is kept under 65-70 C, HSF, motherboard FSB, memory, PSU, ... are assumed not to be limiting the stablity of the system.)

In conjuction with the MHz gain from 10%, 20%, 30% over voltage, one can pick and chose the tradeoff between MHz gain and the reduction of statistical expectancy of CPU failure time.

If one plans to use the CPU for 20 years, or if one is not comfortable of using a 30% higher voltage at which CPU is working above the break-even point (10MHz/C) of frequency and temperature (on air), one would not lose too much MHz even the Vcore is lowered by 10% (~150 mV) at that level, estimated by about 100 MHz. For practical reason, apart from short term benchmarking and fun, trading 100 MHz for 150 mV lower in Vcore is justified.

CPU voltage: from stock to max absolute, from efficient overclocking to diminishing return

1. For Tbred B/Barton, the default voltage ratings (stock voltage) are
- For mobile Barton, 1.45 V
- DLT3C 1.5 V
- DUT3C 1.6 V
- DKT3C 1.65 V
This is the default voltage rating AMD recommends to use.


2. The max absolute voltages that AMD put up are:
Quoted from AMD:
"The AMD Athlon XP processor model 8 should not be subjected to conditions exceeding the absolute ratings, as such conditions can adversely affect long-term reliability or result in functional damage."

- For DLT3C, e.g. 1700+ DLT3C
Vcc_core_dc_max = 1.5 + 0.05 = 1.55 V
The absolute rating for Vcore = 1.55 + 0.5 = 2.05 V

- For DUT3C, e.g. 1700+ DUT3C, 2100+
Vcc_core_dc_max = 1.6 + 0.05 = 1.65 V
The absolute rating for Vcore = 1.65 + 0.5 = 2.15 V

- For DKT3C and Barton, e.g. 2500+, 3200+
Vcc_core_dc_max = 1.65 + 0.05 = 1.70 V
The absolute rating for Vcore = 1.70 + 0.5 = 2.20 V
Ref:
Max Vcore for Tbred B and Barton (page 5)
How much voltage can be applied to a CPU (page 5)


3. For overclocking, the "efficient overclocking voltage" that gives the most overclocking frequency and keeps temperature below diminishing return is
- between 1.5 to 1.85 V for DLT3C and mobile Barton,
- between 1.6 to 1.95 V for DKT3C and desktop Barton
getting about 100 - 130 MHz per 100 mV.
Ref:
General rules on voltage and temperature for CPU overclocking (page 16)


4. If one needs to get the last MHz (last stable 100 MHz) from the CPU, then the CPU has to operate above the "efficient overclocking voltage" and below the "max absolute voltage" . The CPU would have to operate in the diminishing return regime in which every mV of voltage added to speed up the CPU frequency would be counter-acted by the heat increase which in turn slow down the CPU. The return of MHz from voltage is small (< 30 MHz per 100 mV, < 10 MHz / C) and is costly in term of cooling, power supply in this operating range.

This voltage range is recommended for benchmark testing and competition, and not necessary for 24/7 usage. If one has only a CPU to rely on, don't operate it constantly in this voltage range."..........




LOL 8)

[bemauri]

Complimenti per la citazione e,visto che 7 anni fa nasceva il K6 (1), mi sembra che si possa stare piuttosto tranquilli anche over-voltando un po'
il processore magari tenendolo il + fresco possibile.

[MORETTOSA]

be cabernet poi devi calcolare la casistica
il tuo o il mio procio puo morire anche per circostanze misteriose adesso oppure tra 50 anni

[swarzypower]

ciao vorrei sapere come posso aumentare la frequenza della mia cpu
amd 2200 xp premetto che ho gia effettuato uno smanettamento di questa dal bios della scheda madre (km- 400 dell ects ) portando il bus da 133MHz a 140MHz .ottenendo un incremento da 1,7 GHz a 1,9 GHz .ti dico che ho provato ad alzarlo a 145 e ti diro che era stabile ma a volte faceva capricci.superati i 146 il computer si bloccava costringendomi a resettare il bios.come posso fare? devo aumentare il voltaggio ti prego aiutami