EXHIBIT 5.1

               [Bartlit Beck Herman Palenchar & Scott letterhead]

March 29, 2000

Aavid Thermal Technologies, Inc.
Aavid Thermal Products, Inc.
Thermalloy, Inc.
Thermalloy Investment Co., Inc.
Aavid Thermalloy, LLC
Applied Thermal Technologies, LLC
Aavid Thermalloy of Texas, LLC
Aavid Thermalloy SW, LLC
Fluent Holdings, Inc.
One Eagle Square, Suite 509
Concord, New Hampshire 03301

           Re: Registration on Form S-4

Ladies and Gentlemen:

    We have acted as special counsel to Aavid Thermal Technologies, Inc., a
Delaware corporation (the "Company"), Aavid Thermal Products, Inc., a Delaware
corporation ("ATP, Inc."), Thermalloy, Inc., a Delaware corporation
("Thermalloy"), Thermalloy Investment Co., Inc., a Delaware corporation ("TIC"),
Aavid Thermalloy, LLC, a Delaware limited liability company ("AT LLC"), Applied
Thermal Technologies, LLC, a Delaware limited liability company ("Applied"),
Aavid Thermalloy of Texas, LLC, a Delaware limited liability company ("Aavid
Texas"), Aavid Thermalloy SW, LLC, a Delaware limited liability company ("Aavid
SW"), and Fluent Holdings, Inc., a Delaware corporation ("Fluent" and, together
with ATP, Inc., Thermalloy, TIC, AT LLC, Applied, Aavid Texas, Aavid SW and
Fluent, the "Guarantors" and, together with the Company, the "Registrants"), in
connection with the proposed registration by the Company of up to $150,000,000
in aggregate principal amount of its 12 3/4% Senior Subordinated Notes due 2007,
Series B (the "Exchange Notes"), pursuant to a Registration Statement on Form
S-4 (No. 333- 33126) originally filed with the Securities and Exchange
Commission (the "Commission") on March 23, 2000, under the Securities Act of
1933, as amended (the "Act") (such Registration Statement, as amended or
supplemented, is hereinafter referred to as the "Registration Statement"). The
obligations of the Company under the Exchange Notes will be guaranteed by each
of the Guarantors (the "Guarantees"). The Exchange Notes and the Guarantees are
to be issued pursuant to the Indenture, dated as of February 2, 2000 (the
"Indenture"), among the Company, the Guarantors and Bankers Trust Company, as
trustee. The Exchange Notes and the Guarantees are to be issued in exchange for
and in replacement of the Company's outstanding 12 3/4% Senior Subordinated
Notes due 2007 (the "Old Notes"), of which $150,000,000 in aggregate principal
amount is outstanding.

    This opinion is being furnished in accordance with the requirements of Item
601(b)(5) of Regulation S-K under the Act.

    In arriving at the opinion expressed below we have examined and relied on,
among other things, the following:

    -  the Registration Statement;

    -  executed copies of each of (i) the Indenture and (ii) the Registration
       Rights Agreement, dated as of February 2, 2000, among the Company, the
       Guarantors, CIBC World Markets Corp. and FleetBoston Robertson Stephens
       Inc.;

    -  forms of the Exchange Notes and the Guarantees;

    -  the respective certificates of incorporation and by-laws or certificates
       of formation and limited liability company agreements, as applicable, of
       the Registrants, each as presently in effect; and

    -  minutes or records of the corporate or limited liability company
       proceedings of the Registrants with respect to the issuance of the
       Exchange Notes and the Guarantees.

    In addition, we have examined and relied upon the originals or copies,
certified or otherwise identified to our satisfaction, of all such records of
the Company and the Guarantors and such other instruments and certificates of
public officials, officers and representatives of the Company and the Guarantors
and other persons, and we have made such investigations of facts and law, as we
have deemed appropriate as a basis for the opinions expressed below. In our
examination, we have assumed the legal capacity of all natural persons, the
genuineness of the signatures of persons signing all documents and instruments
in connection with which this opinion is rendered, the authenticity of all
documents submitted to us as originals, the conformity to original documents of
all documents submitted to us as copies and the authenticity of the originals of
all documents submitted to us as copies. In making our examination of documents,
we have assumed that the parties thereto (other than the Company and the
Guarantors) had the power (corporate or other) to enter into and perform all
obligations thereunder and have also assumed the due authorization by all
requisite action (corporate or other) and execution and delivery by such parties
of such documents and the validity and binding effect of such documents.

    Our opinion expressed below is subject to the following further
qualifications that we express no opinion as to the applicability of, compliance
with, or effect of:

    -  any bankruptcy, insolvency, reorganization, arrangement, moratorium,
       fraudulent conveyance or other similar laws affecting the enforcement of
       creditors rights generally;

    -  general principles of equity (regardless of whether enforcement is
       considered in a proceeding at law or in equity); or

    -  public policy considerations which may limit the rights of parties to
       obtain certain remedies.

    Based upon and subject to the foregoing, we are of the opinion that when (i)
the Registration Statement becomes effective, (ii) the Indenture has been
qualified under the Trust Indenture Act of 1939, as amended, and (iii) the
Exchange Notes and the Guarantees have been duly executed and, in the case of
the Exchange Notes, authenticated in accordance with the terms of the Indenture
and delivered to the purchasers thereof in exchange for the Old Notes, the
Exchange Notes and the Guarantees will be valid and binding obligations of the
Registrants, enforceable against the Registrants in accordance with their terms.

    We are admitted to practice in the State of Colorado, and express no opinion
whatsoever with respect to any laws other than the internal laws of the State of
Colorado, the federal laws of the United States of America and the General
Corporation Law of the State of Delaware. For the purpose of furnishing this
letter, we have assumed that the internal law of the State of New York is the
same as the internal law of the State of Colorado in all respects material to
this letter.

    We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement. We also consent to the reference to our
firm under the caption "Legal Matters" in the Registration Statement. In giving
this consent, we do not thereby admit that we are included in the category of
persons whose consent is required under Section 7 of the Act or the rules and
regulations of the Commission.

    The foregoing opinions are limited to the specific issues addressed and to
laws existing on the date hereof. By rendering our opinion, we do not undertake
to advise you with respect to any other matter or of any change in such laws or
in the interpretations thereof which may occur after the date hereof.

    This opinion is furnished to you in connection with the filing of the
Registration Statement and is not to be used, circulated, quoted or otherwise
relied upon for any other purpose.

                                          Very truly yours,
                                          /s/ BARTLIT BECK HERMAN PALENCHAR &
                                              SCOTT