E8400/E8500 overclocking thread! - Page 13

Unixlord · 10th Aug 2008, 03:05 PM

Why is it desgined to be convex? Wouldn't better contact result in better heat transfer?

PsYkHoTiK · 10th Aug 2008, 03:38 PM

I think its because the IHS is not perfectly flat (usually concave). I know a popular thing to do with waterblocks is to bow the surface with thicker washers.

Unixlord · 10th Aug 2008, 03:55 PM

Well anyone lapping their heatsink will probably lap the IHS of their cpu too. The thing is, while the line down the middle is slightly concave, the TRUE is just too convex to make proper contact. This can be verified by removing the HS after mounting.

Chai · 10th Aug 2008, 07:50 PM

Don't forget, metal will still flex under intense mounting pressure. A little more convex is better than concave surface without contact on the most important area, the center. That's why manufacturer has started making convex surfaces. Swiftech, Thermalright were very famous for excellent finishing. Why would they do that if it wasn't a good idea?

Max_87 · 10th Aug 2008, 09:19 PM

Why convex? The answer is very simple: to increase the mounting pressure at the center of IHS. (which is the hottest spot on the processor)

Let's compare convex base vs flat base (let's just assume the IHS is flat or just slightly uneven).

By making the base convex, you are basically reducing the area of contact between the base and the IHS. Does this mean you will get worse temp? Nope, not really.

Because: Pressure = Force / Area

Assume the same amount of force is coming from the mounting mechanism for both convex base and flat base waterblock/heatsink. By reducing the area of contact, you are essentially increasing the amount of pressure applied on the IHS, which is concentrated at the center of the IHS. This effectively lowers the thermal resistance between the base/TIM/IHS. This is why a bowed Apogee GT outperforms a flat Apogee GT waterblock easily and by a significant margin, one of the many examples.

Max_87 · 10th Aug 2008, 09:41 PM

Quote:

Originally Posted by Chai

Don't forget, metal will still flex under intense mounting pressure. A little more convex is better than concave surface without contact on the most important area, the center. That's why manufacturer has started making convex surfaces. Swiftech, Thermalright were very famous for excellent finishing. Why would they do that if it wasn't a good idea?

If you actually applied THAT much mounting pressure to the point that it causes the copper base to flex, it won't return to it's original shape anymore because copper has quite low yield strength (not sure if this is the correct term). If that happens, you won't be able to use the waterblock anymore. I don't think it's going to happen on heatsink base because they are just too thick, no matter how hard you try.

The bases (particularly waterblocks) are usually thick enough and shouldn't flex if you just hand tighten the nuts + bolts, even if you try really hard.

Unixlord · 11th Aug 2008, 01:04 AM

Thanks for the info guys. How does the thermalright IFX-14 compare to the ultra extreme?

Max_87 · 11th Aug 2008, 08:46 PM

AFAIK, Ultra 120 Extreme is slightly better than IFX-14.

PsYkHoTiK · 6th Sep 2008, 12:38 AM

So yeah.

I are teh slow.

3.8GHz on stock 1.2v (still finding stock voltage baseline).
CPU-Z Validator 2.1

8 hour prime stable (I also used IntelBurnTest as a quick acid test).

Still pushing (and loving it).

PsYkHoTiK · 6th Sep 2008, 02:20 AM

4.2GHz (1.32v) and counting!

20 Passes IntelBurnTest (I will save a big prime95 for last).

CPU-Z Validator 2.1

10th Aug 2008, 03:05 PM	#121 (permalink)
Unixlord I'm a regular Join Date: 26 Jun 2008 Posts: 286 Reputation: 98 Rep Power: 1	Why is it desgined to be convex? Wouldn't better contact result in better heat transfer? __________________ Intel E8400 @ 3.6GHz + Zerotherm Zen FZ120 \| ASUS Rampage Formula \| OCZ 2x1GB DDR2-800 \| Gainward GeForce 8800GT + Zalman VF1000 \| PC Power and Cooling Silencer 750W \| Thermaltake Armor VA8003SWA

10th Aug 2008, 03:38 PM	#122 (permalink)
PsYkHoTiK "Little" Devil Join Date: 8 Apr 2004 Location: On the "throne" Posts: 14,290 Reputation: 4003 Rep Power: 59	I think its because the IHS is not perfectly flat (usually concave). I know a popular thing to do with waterblocks is to bow the surface with thicker washers. __________________ Intel SLAPL 4.3GHz @ 1.35v : 2x2GB OCZ Platinum DDR2 1066 : Asus P5K Premium : WD Raptor X : G92 8800GTS 512mb 800MHz Core WIP : XFi Platinum : Silverstone OP650 : Silverstone TJ-07 : Vista Ultimate Edition : Dtek FuZion CPU : Swiftech MCW60 : MCP655 : Thermochill PA120.3 w Scythe Ultra Kaze : Tygon R3603 1/2" ID 3/4" OD CPU-Z: SLAPL : SLA9U : FX-55 : DDR 600 : VX www.techarp.com

10th Aug 2008, 03:55 PM	#123 (permalink)
Unixlord I'm a regular Join Date: 26 Jun 2008 Posts: 286 Reputation: 98 Rep Power: 1	Well anyone lapping their heatsink will probably lap the IHS of their cpu too. The thing is, while the line down the middle is slightly concave, the TRUE is just too convex to make proper contact. This can be verified by removing the HS after mounting. __________________ Intel E8400 @ 3.6GHz + Zerotherm Zen FZ120 \| ASUS Rampage Formula \| OCZ 2x1GB DDR2-800 \| Gainward GeForce 8800GT + Zalman VF1000 \| PC Power and Cooling Silencer 750W \| Thermaltake Armor VA8003SWA

10th Aug 2008, 07:50 PM	#124 (permalink)
Chai Administrator Join Date: 6 Oct 2002 Location: Maranello Posts: 26,655 Reputation: 3984 Rep Power: 72	Don't forget, metal will still flex under intense mounting pressure. A little more convex is better than concave surface without contact on the most important area, the center. That's why manufacturer has started making convex surfaces. Swiftech, Thermalright were very famous for excellent finishing. Why would they do that if it wasn't a good idea? __________________ Chai (Contributor & Forum Admin) http://www.techarp.com/

10th Aug 2008, 09:19 PM	#125 (permalink)
Max_87 h@x! Join Date: 11 Aug 2003 Location: Sarawak, Malaysia. Posts: 11,261 Reputation: 2024 Rep Power: 37	Why convex? The answer is very simple: to increase the mounting pressure at the center of IHS. (which is the hottest spot on the processor) Let's compare convex base vs flat base (let's just assume the IHS is flat or just slightly uneven). By making the base convex, you are basically reducing the area of contact between the base and the IHS. Does this mean you will get worse temp? Nope, not really. Because: Pressure = Force / Area Assume the same amount of force is coming from the mounting mechanism for both convex base and flat base waterblock/heatsink. By reducing the area of contact, you are essentially increasing the amount of pressure applied on the IHS, which is concentrated at the center of the IHS. This effectively lowers the thermal resistance between the base/TIM/IHS. This is why a bowed Apogee GT outperforms a flat Apogee GT waterblock easily and by a significant margin, one of the many examples. __________________ Max_87 Tech ARP http://www.techarp.com P4 630 / Abit IP35 Pro / G.Skill F2-8000CL5-4GBPQ / Radeon X1800 / Barracuda 7200.9 120GB / 7200.10 320GB x2 / Caviar SE16 WD5000AAKS / WD6400AAKS x2 / Dell 2007FP x2 / Silverstone ST56F

11th Aug 2008, 01:04 AM	#127 (permalink)
Unixlord I'm a regular Join Date: 26 Jun 2008 Posts: 286 Reputation: 98 Rep Power: 1	Thanks for the info guys. How does the thermalright IFX-14 compare to the ultra extreme? __________________ Intel E8400 @ 3.6GHz + Zerotherm Zen FZ120 \| ASUS Rampage Formula \| OCZ 2x1GB DDR2-800 \| Gainward GeForce 8800GT + Zalman VF1000 \| PC Power and Cooling Silencer 750W \| Thermaltake Armor VA8003SWA

11th Aug 2008, 08:46 PM	#128 (permalink)
Max_87 h@x! Join Date: 11 Aug 2003 Location: Sarawak, Malaysia. Posts: 11,261 Reputation: 2024 Rep Power: 37	AFAIK, Ultra 120 Extreme is slightly better than IFX-14. __________________ Max_87 Tech ARP http://www.techarp.com P4 630 / Abit IP35 Pro / G.Skill F2-8000CL5-4GBPQ / Radeon X1800 / Barracuda 7200.9 120GB / 7200.10 320GB x2 / Caviar SE16 WD5000AAKS / WD6400AAKS x2 / Dell 2007FP x2 / Silverstone ST56F

6th Sep 2008, 12:38 AM	#129 (permalink)
PsYkHoTiK "Little" Devil Join Date: 8 Apr 2004 Location: On the "throne" Posts: 14,290 Reputation: 4003 Rep Power: 59	So yeah. I are teh slow. 3.8GHz on stock 1.2v (still finding stock voltage baseline). CPU-Z Validator 2.1 8 hour prime stable (I also used IntelBurnTest as a quick acid test). Still pushing (and loving it). __________________ Intel SLAPL 4.3GHz @ 1.35v : 2x2GB OCZ Platinum DDR2 1066 : Asus P5K Premium : WD Raptor X : G92 8800GTS 512mb 800MHz Core WIP : XFi Platinum : Silverstone OP650 : Silverstone TJ-07 : Vista Ultimate Edition : Dtek FuZion CPU : Swiftech MCW60 : MCP655 : Thermochill PA120.3 w Scythe Ultra Kaze : Tygon R3603 1/2" ID 3/4" OD CPU-Z: SLAPL : SLA9U : FX-55 : DDR 600 : VX www.techarp.com

6th Sep 2008, 02:20 AM	#130 (permalink)
PsYkHoTiK "Little" Devil Join Date: 8 Apr 2004 Location: On the "throne" Posts: 14,290 Reputation: 4003 Rep Power: 59	4.2GHz (1.32v) and counting! 20 Passes IntelBurnTest (I will save a big prime95 for last). CPU-Z Validator 2.1 __________________ Intel SLAPL 4.3GHz @ 1.35v : 2x2GB OCZ Platinum DDR2 1066 : Asus P5K Premium : WD Raptor X : G92 8800GTS 512mb 800MHz Core WIP : XFi Platinum : Silverstone OP650 : Silverstone TJ-07 : Vista Ultimate Edition : Dtek FuZion CPU : Swiftech MCW60 : MCP655 : Thermochill PA120.3 w Scythe Ultra Kaze : Tygon R3603 1/2" ID 3/4" OD CPU-Z: SLAPL : SLA9U : FX-55 : DDR 600 : VX www.techarp.com

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