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PLX temperature montor MVE

billyray
Level 7
I am just about finished building a Maximus V Extreme pc with a Sapphire HD7970 dual x graphics card installed in PCIe Slot 2. No OS on hdd yet. Just using the BIOS UEFI screens right now. I noticed that the plx temperature monitor is saying 50 degrees C. (although very stable.) When I touch the PLX chip its not hot or even warm. What is the PLX temperature monitoring on the MVE board? I mean, where is that 50 deg. C. coming from on the board? The CPU and board are nice and cool, around 80 degrees F. Are those heatsink things on the mobo hiding it? They feel warm, but not hot.

I Noticed that the temperature cutoff is 105 degrees, so I have to assume that is centigrade, since mine is registering 122 deg. F. and nothing is shutting down.

Is this a fairly normal temperature for the PLX? (no overclocking is currently active)

Thanks for any comments!
Notebook: Asus G73jh with 8 GB ram, 160GB Intel ssd, 500GB 2nd drive.
Desktop: Asus Maximus V Extreme, BIOS 1501, 32 GB Corsair Vengeance, with Sapphire HD 7970 Dual X OC, Corsair H80i water cooling, Thermaltake Toughpower Grand 1200W PSU, Cooler Master HAF X tower case on wheels! :cool: built 9/28/12
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6 REPLIES 6

SUKARA
Level 10
These temperatures, after the detection of multiple sensors on the motherboard, an objective the average

If you still worry about it, install your VGA to FIRST red PCIE slot (16x) or black PCIE slot (x8) to deactivate PLX chip 🙂

Macforth
Level 9
Billyray, just a few notes first of all regarding the PLX chip in your Maximus V Extreme. Your motherboard is a 1155 platform with a Z77 chipset. Amongst other things, this means that the CPU/Z77 can talk to 16 lanes through to the PCIe type device. As Asus wished to offer more lanes to allow for 4 way SLI, they included what we call a PLX chip on the motherboard. The actual PLX chip used is a PLX PEX 8747.
This allows the MVE to run 32 lanes (at PCIe 3.0)

However, it was up to Asus to design how they were going to do this, and if we read the manual carefully, we can see that the lanes that use the Z77 only (termed native) are the Red slot 1 (named PCIe 3.0/2.0_x16/x8_1 in your manual), and the Black slot 2b (named PCIe 3.0/2.0_x8_2B in your manual).

The way they have designed this area means that if you only use the slots that use the 16 native lanes (the ones going directly to the Z77), the PLX is not needed, and in fact will not "turn on". If you happen to use another slot with a single (even if it's a dual on a single), apart from the two above, you will turn on the PLX Intergrated Circuit. When the PLX chip is running, it consumes about 8 watts of power typically. Not much, sure, but the heat generated in a small 27mm x 27mm chip could see it rise to 50C.

Given your choice of Video card, you can now see the reason why you would be well advised to use one of the two slots mentioned above, so that you run "native" lanes, rather than turn the PLX on. I would recommend Red slot one, because, as you can see on page 1-26 of your manual, the first red slot will give you x16 3.0 PCIe, while 2B will give you x8 3.0 PCIe. I would only use 2B if there is a fitting problem...praps interference with other hardware.

Two other matters you mention. The first is the positioning of the PLX.......it's not under anything, but is positioned between the 3rd and 4th red PCIe slots, just above the small black PCIe x4 slot. The second concerns the "cutoff" temperature of 105 degrees. This is associated with the PLX, but is also the temperature, that if the CPU gets to, it will shut down.

Hope this assists.
Just finishing TJ 11 WC.. trying to control cooling via total PWM
Asus Max V Extreme
Intel 3770K
Corsair 16gig Platinum 1866
2 X GTX 690 (EVGA) with aftermarket EVGA water blocks and backplates
Samsung 830 Series 512GB + 3 WD mechanical HD's
Swiftech Apogee Drive II
Swiftech MCP35X2
Alphacool NexXxos UT60's quad, triple and single 120's
Rad fans 11 x NF-F12 PWM
Corsair 1200i PSU
Swiftech Maelstrom
AFT Pro-57U card reader

Thanks for the terrific replies! 😉 I noticed that Asus does seem to recommend using slot 1 first for the graphics card. I was hesitant because I thought it would crowd the cpu area and increase the heat. But I couldn't have been more wrong! I took everyone's advice (especially with Macforth's great explanation) and moved the graphics card to slot 1. Now the PLX chip is running at ambient mobo temps (which are very cool) and the cpu is running even cooler!

I had to admit that any simple change that would result in less used power (even 8 watts) and lowered a temp on the chip, and getting native mode graphics handling would be worth checking out.
Notebook: Asus G73jh with 8 GB ram, 160GB Intel ssd, 500GB 2nd drive.
Desktop: Asus Maximus V Extreme, BIOS 1501, 32 GB Corsair Vengeance, with Sapphire HD 7970 Dual X OC, Corsair H80i water cooling, Thermaltake Toughpower Grand 1200W PSU, Cooler Master HAF X tower case on wheels! :cool: built 9/28/12

Gman4097
Level 7
what if im running my ati 7870 in 1a and 2a crossfired ? why is my plx temp go to 50c or above when im gaming? right now on idle it says 47c. why is that can I make it run cooler ? Ive ordered a water cooler block for my board that asus recomends instead of the pipe cooling thats installed will that help? Im koolance water cooled with resevoir rp-452x2 and dual 450 s pumps and 1/2 id 3/4 od hose and 2 radiators far as cpu. also have a 1k mushkin joule split rail power supply . ,y mobo dont go aboove 33c and cpu dont get aboive 45c at idle 33c

I think because you are running the 2nd card in a non native slot.......... the 2nd card should be in 2B

It is the 3rd slot from the CPU and is colored Black!
Just finishing TJ 11 WC.. trying to control cooling via total PWM
Asus Max V Extreme
Intel 3770K
Corsair 16gig Platinum 1866
2 X GTX 690 (EVGA) with aftermarket EVGA water blocks and backplates
Samsung 830 Series 512GB + 3 WD mechanical HD's
Swiftech Apogee Drive II
Swiftech MCP35X2
Alphacool NexXxos UT60's quad, triple and single 120's
Rad fans 11 x NF-F12 PWM
Corsair 1200i PSU
Swiftech Maelstrom
AFT Pro-57U card reader